DUGAR HYDRO POWER LIMITED (A Joint Venture of Tata …environmentclearance.nic.in/writereaddata/Online/TOR/0… · · 2014-11-11Dugar Hydro Power Limited (A Joint Venture of Tata

DUGAR HYDRO POWER LIMITED (A Joint Venture of Tata Power & S N Power)

DUGAR HYDRO ELECTRIC PROJECT CHAMBA DISTRICT, HIMACHAL PRADESH | INDIA

DRAFT DETAILED PROJECT REPORT

VOLUME – I MAIN REPORT

November 2014

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Index Dugar Hydro Electric Project 1

DPR – Volume I: Main Report November 2014

DUGAR HYDRO ELECTRIC PROJECT

DRAFT DETAILED PROJECT REPORT

VOLUME I : MAIN REPORT

VOLUME II : HYDROLOGY

VOLUME III : GEOLOGICAL AND GEOTECHNICAL STUDIES

VOLUME IV : DRAWINGS

VOLUME V : APPENDIXVOLUME V [A] : GLOF STUDYVOLUME V [B] : ROUTE SURVEY REPORT



TABLE OF CONTENT

1 INTRODUCTION .......................................................................... 1.2 1.1 GENERAL ..................................................................................................................................................... 1.2 1.2 PROJECT LOCATION & ACCESS ........................................................................................................ 1.2 1.3 CLIMATIC CONDITION .......................................................................................................................... 1.3 1.4 TOPOGRAPHY & PHYSIOGRAPHY ................................................................................................... 1.4 1.5 GEOLOGY .................................................................................................................................................... 1.4 1.6 HISTORICAL BACKGROUND OF THE PROJECT ........................................................................... 1.5 1.7 NEED OF THE PROJECT ......................................................................................................................... 1.7 1.8 ALTERNATIVE STUDY ............................................................................................................................. 1.7 1.9 INTER STATE, INTERNATIONAL OR DEFENCE ASPECT ........................................................... 1.8

2 SALIENT FEATURES ..................................................................... 2.2 2.1 PROJECT LOCATION .............................................................................................................................. 2.2 2.2 HYDROLOGY ............................................................................................................................................. 2.2 2.3 RESERVOIR ................................................................................................................................................. 2.2 2.4 DAM AND SPILLWAYS .......................................................................................................................... 2.3 2.5 RIVER DIVERSION AND DIVERSION TUNNEL (DT) ................................................................... 2.3 2.6 POWER INTAKE (ON LEFT BANK) ..................................................................................................... 2.4 2.7 PRESSURE TUNNEL/ PRESSURE SHAFT ......................................................................................... 2.4 2.8 POWERHOUSE .......................................................................................................................................... 2.5 2.9 TRANSFORMER CAVERN ..................................................................................................................... 2.6 2.10 SURGE CAVERN/DRAFT TUBE GATE OPERATION CHAMBER .............................................. 2.7 2.11 TAIL RACE TUNNELS (TRT) .................................................................................................................. 2.7 2.12 POWER BENEFITS .................................................................................................................................... 2.8

3 JUSTIFICATION OF PROJECT ..................................................... 3.4 3.1 POWER SCENARIO IN INDIA .............................................................................................................. 3.4 3.2 POWER SCENARIO IN THE NORTHERN REGION ...................................................................... 3.7 3.3 POWER SCENARIO IN HIMACHAL PRADESH ............................................................................ 3.13 3.4 HYDRO POWER DEVELOPMENT ..................................................................................................... 3.16 3.5 NECESSITY AND JUSTIFICATION .................................................................................................... 3.19 3.6 POWER EVACUATION FOR THE PROJECT .................................................................................. 3.22

4 BASIN DEVELOPMENT ................................................................ 4.2 4.1 MAJOR RIVER SYSTEMS ....................................................................................................................... 4.2 4.2 ASSESSMENT OF HYDRO POWER POTENTIAL ........................................................................... 4.2



4.3 INDUS BASIN ............................................................................................................................................ 4.4 4.4 CHENAB BASIN ........................................................................................................................................ 4.5 4.5 FITMENT OF DUGAR HEP IN CHENAB BASIN DEVELOPMENT ............................................ 4.6

5 INTERNATIONAL ASPECT - INDUS WATER TREATY ............... 5.2 5.1 GENERAL ..................................................................................................................................................... 5.2 5.2 THE TREATY ............................................................................................................................................... 5.3 5.3 PROVISIONS REGARDING WESTERN RIVERS .............................................................................. 5.4 5.4 HYDROELECTRIC PROJECTS ON WESTERN RIVERS ................................................................. 5.4 5.5 COMMUNICATION WITH PAKISTAN ............................................................................................ 5.10 5.6 SETTLEMENT OF DIFFERENCES AND DISPUTES ...................................................................... 5.11

6 SURVEY & INVESTIGATIONS ..................................................... 6.3 6.1 TOPOGRAPHICAL SURVEY .................................................................................................................. 6.3 6.2 GEOLOGICAL AND GEOTECHNICAL INVESTIGATIONS ........................................................ 6.11 6.3 ARCHAEOLOGICAL & MINERAL SURVEY .................................................................................... 6.17 6.4 COMMUNICATION SURVEY ............................................................................................................. 6.17 6.5 CONSTRUCTION MATERIAL SURVEY ........................................................................................... 6.18 6.6 HYDRLOGICAL & METEOROLOGICAL INVESTIGATIONS ..................................................... 6.18

7 HYDROLOGY ................................................................................ 7.8 7.1 GENERAL ..................................................................................................................................................... 7.8 7.2 DATA VALIDATION AND CONSISTENCY CHECK ..................................................................... 7.29 7.3 WATER AVAILABILITY .......................................................................................................................... 7.58 7.4 DESIGN FLOOD ...................................................................................................................................... 7.67 7.5 DESIGN FLOOD FOR RIVER DIVERSION WORKS ..................................................................... 7.90 7.6 SEDIMENTATION STUDY ................................................................................................................... 7.99 7.7 LIMITATIONS OF STUDY ................................................................................................................. 7.104

8 GEOLOGY ................................................................................... 8.10 8.1 INTRODUCTION ..................................................................................................................................... 8.10 8.2 REGIONAL GEOLOGY ........................................................................................................................... 8.14 8.3 SEISMICITY AND SEISMOTECTONICS .......................................................................................... 8.19 8.4 SITE GEOLOGY ........................................................................................................................................ 8.25 8.5 ALTERNATIVES STUDIES ..................................................................................................................... 8.42 8.6 GEOLOGICAL & GEOTECHNICAL INVESTIGATIONS .............................................................. 8.45 8.7 GEOLOGICAL & GEOTECHNICAL ASSESSMENT OF PROJECT COMPONENTS ........... 8.72 8.8 RESRVOIR RIM STABILITY ............................................................................................................... 8.106



8.9 CONCLUSIONS .................................................................................................................................... 8.119

10 POWER POTENTIAL & INSTALLED CAPACITY ....................... 10.4 10.1 INTRODUCTION ..................................................................................................................................... 10.4 10.2 SALIENT FEATURES ............................................................................................................................... 10.4 10.3 POWER POTENTIAL STUDY ............................................................................................................... 10.7

11 DESIGN OF CIVIL STRUCTURES ............................................... 11.5 11.1 GENERAL ................................................................................................................................................... 11.5 11.1 PONDAGE ................................................................................................................................................. 11.5 11.2 DAM AND APPURTENANT STRUCTURES ................................................................................... 11.7 11.3 RIVER DIVERSION STRUCTURES .................................................................................................. 11.15 11.4 POWER INTAKES ................................................................................................................................. 11.25 11.5 PRESSURE SHAFTS ............................................................................................................................. 11.26 11.6 POWERHOUSE AND TRANSFORMER CAVERNS ................................................................... 11.26 11.7 SURGE & DRAFT TUBE GATE CAVERN ...................................................................................... 11.28 11.8 TAILRACE TUNNEL ............................................................................................................................. 11.30 11.9 POTHEAD YARD .................................................................................................................................. 11.31



LIST OF TABLES

Table 3.1: Long Term Region wise Forecast ...................................................................................................... 3.6 Table 3.2: Installed Capacity of Northern Region as on 31st December, 2013 in MW .................... 3.7 Table 3.3: Availability/Requirement of Energy & Peak Power in Northern Region during Past Decade (2002-03 to 2011-12) ................................................................................................................................... 3.8 Table 3.4: Growth in Energy Generation in Northern Region during Past Decade (2002-03 to 2011-12) .......................................................................................................................................................................... 3.10 Table 3.5: Growth in Installed Capacity in Northern Region during Past Decade (2002-03 to 2011-12) .......................................................................................................................................................................... 3.10 Table 3.6: Energy and Peak Load Demand for the Northern Region (Period 2016– 2022) ............... 3.12 Table 3.7: Installed Capacity of Himachal Pradesh as on 31st December, 2013 in MW ............... 3.13 Table 3.8: Energy and Peak Load Demand for Himachal Pradesh (Period 2016 – 2022) ............ 3.16 Table 3.9: Capacity Addition Planned during 11th Plan for All India in MW ..................................... 3.18 Table 3.10: Projected Electricity Demand of All India ................................................................................ 3.19 Table 4.1: Basin-wise Hydroelectric Potential as per First Survey ............................................................ 4.2 Table 4.2: Basin-wise Hydroelectric Potential as per Re-assessment Study ........................................ 4.3 Table 4.3: Hydroelectric Potential of Indus Basin ............................................................................................ 4.4 Table 4.4: Hydro Power Projects on Chenab River ......................................................................................... 4.6 Table 5.1: Aggregate Storage Capacity Allotted to India ............................................................................ 5.9 Table 6.1: Survey Station Established by Survey of India ............................................................................ 6.4 Table 6.2: Control Stations in the Project Area ................................................................................................ 6.8 Table 6.3: Reference SOI Bench Mark ............................................................................................................... 6.10 Table 6.5: Details of Geological Plan and Sections ...................................................................................... 6.12 Table 6.6: The Details of Borehole Investigations Completed at Dugar HEP ................................... 6.13 Table 6.7: Details of Exploratory Drifts Excavated at Dugar Project Area. ......................................... 6.14 Table 6.8: Details of Seismic Refraction Traversing (SRT) at Dugar Project Area ........................... 6.15 Table 6.9: Details of Electrical Resistivity Traversing (ERT) at Dugar Project Area ......................... 6.15 Table 6.10: Details of In-situ Rock Mechanics Tests Completed/ Proposed for Dam/Powerhouse Exploratory Drifts ......................................................................................................................................................... 6.16 Table 7.1: Project Parameters .................................................................................................................................. 7.8 Table 7.2: Hypsometric Data at Dugar Diversion Site ................................................................................ 7.11 Table 7.3: Estimation of Zero Degree Isotherms .......................................................................................... 7.15 Table 7.4: Bar Chart showing Availability of Discharge & Rainfall Data ............................................. 7.17 Table 7.5: Catchment Characteristic of various G&D sites ....................................................................... 7.18 Table 7.6: Mean Monthly Percentage of Rainfall (Oct 2011 –Dec 2012) at Killar ........................... 7.23 Table 7.7: Mean Monthly Percentage of Rainfall (1951-2001) at Koksar ........................................... 7.24 Table 7.8: Mean Monthly Percentage of Rainfall (1951-2002) at Gondla .......................................... 7.25 Table 7.9: Mean Monthly Percentage of Rainfall at Keylong .................................................................. 7.26 Table 7.10: Mean Monthly Temperature ......................................................................................................... 7.27



Table 7.11: Specific Yield at G&D Sites ............................................................................................................ 7.56 Table 7.12: Daily Observed Discharge Record of Chenab River in at Dugar HEP .......................... 7.61 Table 7.13: 10-Daily flow summary at Dugar HEP ....................................................................................... 7.62 Table 7.14: Detail of 50% and 90% Dependable Flow Year ..................................................................... 7.64 Table 7.15: Dependable Flow at Dugar Project and various G&D Sites in Chenab Basin .......... 7.65 Table 7.16: Unit Hydrograph Ordinates ........................................................................................................... 7.72 Table 7.17: Temporal Distribution ...................................................................................................................... 7.74 Table 7.18: Design Storm for Dugar HEP ........................................................................................................ 7.75 Table 7.19: 12-hr Bells of 24-hr Design Storm .............................................................................................. 7.76 Table 7.20: Design Flood Ordinates at Dugar Dam Site ........................................................................... 7.77 Table 7.21: Design Flood Ordinates at Dugar Dam Site ........................................................................... 7.78 Table 7.22: Observed Annual Maxima Flood Peaks at Udaipur Site .................................................... 7.80 Table 7.23: Details of Tests .................................................................................................................................... 7.86 Table 7.24: Statistical Parameter ......................................................................................................................... 7.86 Table 7.25: Result of Flood Frequency of Annual Observed Flood Peaks of Udaipur .................. 7.87 Table 7.26: Result of Flood Frequency of Annual Instantaneous Flood Peaks of Udaipur ........ 7.87 Table 7.27: Different Return Period Floods at Dugar Diversion Site .................................................... 7.88 Table 7.28: Comparison of Design Flood by Different Approach at Dugar HEP Site ................... 7.89 Table 7.29: Detail of Non-monsoon (Oct-May) Flood Peaks, Udaipur ............................................... 7.92 Table 7.30: Details of Tests .................................................................................................................................... 7.95 Table 7.31: Statistical Parameter, Non-Monsoon ........................................................................................ 7.96 Table 7.32: Result of Flood Frequency of Non monsoon Flood Peaks of Udaipur ....................... 7.96 Table 7.33: Result of Flood Frequency of Non Monsoon Instantaneous Flood Peaks of Udaipur ............................................................................................................................................................................................. 7.97 Table 7.34: Different Return Period Non Monsoon Floods at Dugar Diversion Site .................... 7.97 Table 7.35: Yearly Sediment Rate ..................................................................................................................... 7.100 Table 7.36: Original Elevation-Area-Capacity at Dugar Diversion Site ............................................. 7.101 Table 8.1: Stratigraphic sequence of the area around the project site ............................................... 8.15 Table 8.2: Discontinuity Sets and their Engineering Properties in Dam/Power house sites ......... 8.39 Table 8.3: Discontinuity Sets and their Engineering Properties in Reservoir area ............................ 8.40 Table 8.4: The List of Geological Plan and Sections, enclosed with Volume III-B. ............................ 8.47 Table 8.5: The Details of Borehole Investigations Completed at Duagr Project area ................... 8.49 Table 8.6: In-Situ Permeability Status at Dam Site ...................................................................................... 8.57 Table 8.7: Details of Exploratory Drifts Excavated at Dugar Project Area .......................................... 8.58 Table 8.8: Details of Seismic Refraction Traversing (SRT) at Dugar Project Area. ............................ 8.65 Table 8.9: Details of Electrical Resistivity Traversing (ERT) at Dugar Project Area. .......................... 8.65 Table 8.10: Average representative index properties of core samples. .................................................. 8.66 Table 8.11: Average representative geotechnical parameters. ................................................................. 8.66 Table 8.12: Average representative Elastic Properties of core samples ................................................. 8.67 Table 8.13: Average representative Shear Strength Parameters of core samples ............................. 8.67



Table 8.14: Average representative Shear Wave Velocities of core samples ...................................... 8.67 Table 8.15: Details of in-situ rock mechanics tests conducted/proposed at site ........................... 8.69 Table 8.16: Estimated modulus of deformations of rock mass from Exp. drifts ............................. 8.70 Table 8.17: Estimated Shear Strength Parameters of ‘Rock to Rock’ Interface ............................... 8.70 Table 8.18: Estimated Shear Strength Parameters of ‘Concrete to Rock’ Interface ...................... 8.71 Table 8.19: Shear Seams details, Right Abutment ....................................................................................... 8.78 Table 8.20: Rock mass rating assessment parameters for Dam site ...................................................... 8.82 Table 8.21: Rock mass quality (Q) assessment for Left Abutment of Dam. ..................................... 8.83 Table 8.22: Rock mass quality (Q) assessment for Right Abutment of Dam. ................................... 8.83 Table 8.23: Rock mass classes likely to be encountered in DT. ................................................................ 8.90 Table 8.24: Rock Support measures for Diversion Tunnels. ....................................................................... 8.90 Table 8.25: Rock Mass Rating adopted for Pressure Tunnel/Shaft ...................................................... 8.95 Table 8.26: Rock Mass Quality (Q) adopted for Pressure Tunnel/Shaft ............................................. 8.95 Table 8.27: Rock mass classes likely to be encountered in Pressure Tunnel .................................... 8.95 Table 8.28: Rock Support measures for Pressure Tunnel/Shaft ............................................................. 8.96 Table 8.29: Rock Mass Rating adopted for power house complex .................................................... 8.100 Table 8.30: Rock mass classes likely to be encountered in Powerhouse complex ...................... 8.100 Table 8.31: Primary rock support system designed for Power house complex ............................ 8.101 Table 8.32: Rock mass classes likely to be encountered ......................................................................... 8.103 Table 8.33: Rock Support measures for Tailrace Tunnel ........................................................................... 8.103 Table 10.1: Statistics of 90% & 50% Dependable Years ............................................................................ 10.8 Table 10.2: Annual Unrestricted Energy in Descending Order ............................................................... 10.8 Table 10.3: Pattern of Flow in 50% and 90% Dependable Years ........................................................... 10.9 Table 10.4: Results of Flow Duration Curve .................................................................................................. 10.10 Table 10.5: Required Environmental Flow ..................................................................................................... 10.11 Table 10.6: Data for Area-Capacity Elevation Curve ................................................................................. 10.12 Table 10.7: Pondage Calculations as per IWT .............................................................................................. 10.16 Table 10.8: Results of Incremental Energy Study ....................................................................................... 10.19 Table 10.9: Flow Pattern for Auxiliary Units .................................................................................................. 10.22 Table 10.10: Approximate Weights of E&M Equipment ......................................................................... 10.24 Table 11.1: Features of the Reservoir ................................................................................................................ 11.5 Table 11.2: Main Features of Gravity Dam ...................................................................................................... 11.7 Table 11.3: Characteristics of Low Level and Upper Level Spillway ................................................... 11.10 Table 11.4: Computation of Water Level at Inlet for different DT Diameter .................................. 11.17 Table 11.5: Cost Comparison of Upstream Cofferdam ............................................................................ 11.18 Table 11.6: Cost Comparison for the Diversion Tunnel ........................................................................... 11.19 Table 11.7: Main Features of the Power House Cavern .......................................................................... 11.27 Table 11.8: Main Features of the Downstream Surge Chamber .......................................................... 11.29



LIST OF FIGURES

Figure 1.1: Location of The Project........................................................................................................................ 1.3 Figure 3.1: Shares in Installed Capacity – December 2013 ......................................................................... 3.4 Figure 3.2: Region Wise Power Supply Position during Year 2013-14 .................................................. 3.5 Figure 3.3: Region Wise Peak Demand Position during Year 2013-14 .................................................. 3.5 Figure 3.4: Region Wise Installed Generation Capacity ................................................................................ 3.7 Figure 3.5: Energy Availability and Requirement of Northern Region during Past Decade (2002-03 to 2011-12) ................................................................................................................................................................. 3.9 Figure 3.6: Peak Availability and Requirement of Northern Region during Past Decade (2002-03 to 2011-12) ........................................................................................................................................................................ 3.9 Figure 3.7: Actual Energy Availability and Requirement of Northern Region for FY 2011-12 ............. 3.11 Figure 3.8: Actual Peak Availability and Demand of Northern Region for FY 2011-12 ............... 3.12 Figure 3.9: Energy Availability and Requirement of Himachal Pradesh during Past Decade (2002-03 to 2011-12) ................................................................................................................................................. 3.14 Figure 3.10: Peak Availability and Requirement of Himachal Pradesh during Past Decade (2002-03 to 2011-12) .............................................................................................................................................................. 3.14 Figure 3.11: Actual Energy Availability and Requirement of Himachal Pradesh for FY 2011-12 ............. 3.15 Figure 3.12: Actual Peak Availability and Demand of Himachal Pradesh for FY 2011-12 .................. 3.16 Figure 3.13: Plan-wise Growth and Share of Hydropower ....................................................................... 3.17 Figure 3.14: Planned vs. Actual Commissioned Capacity of All India during 11th Plan ............... 3.18 Figure 3.15: Growth of Per Capita Electricity Consumption .................................................................... 3.20 Figure 3.16: Peak Percentage Deficit of States in Northern Region for FY 2011-12 .................... 3.21 Figure 4.1: Region-wise Distribution of Hydro Potential ............................................................................. 4.4 Figure 4.2: Basin-wise Distribution of Hydro Potential ................................................................................. 4.5 Figure 4.3: Major Hydropower Projects in Chenab Basin ............................................................................ 4.7 Figure 5.1: Rivers of Indus Water System ........................................................................................................... 5.2 Figure 7.1: Digital Elevation Model of the Study Area ............................................................................... 7.10 Figure 7.2: Hypsometric Curve-Distribution of Catchment Area at Proposed Diversion Site ... 7.12 Figure 7.3: A View of Chenab River .................................................................................................................... 7.12 Figure 7.4: Automatic Weather Station at Project Site .............................................................................. 7.20 Figure 7.5: Annual Flow regime of Chenab River at Udaipur .................................................................. 7.21 Figure 7.6: Non-Monsoon Flow Regime of Chenab River at Udaipur ............................................... 7.21 Figure 7.7: Monthly Flow Distribution at Udaipur ....................................................................................... 7.22 Figure 7.8: 10-Daily average Flow Distribution at Udaipur ...................................................................... 7.22 Figure 7.9: Distribution of Mean Monthly Rainfall at Killar ...................................................................... 7.24 Figure 7.10: Distribution of Mean Monthly Rainfall at Koksar ............................................................... 7.25 Figure 7.11: Distribution of Mean Monthly Rainfall at Gondla .............................................................. 7.26 Figure 7.12: Distribution of Mean Monthly Rainfall at Keylong ............................................................ 7.27 Figure 7.13: Mean Monthly Temperature at Killar, Badarwah and Banihal....................................... 7.28



Figure 7.14: Annual Flow Comparison of Udaipur, Gulabgarh and Benzwar ................................... 7.30 Figure 7.15: Mass Curve of Annual Flow of Chenab River at Udaipur ................................................ 7.31 Figure 7.16: Mass Curve of Annual Flow of Chenab River at Gulabgarh ........................................... 7.31 Figure 7.17: Mass Curve of Annual Flow of Chenab River at Benzwar ............................................... 7.32 Figure 7.18: Double Mass Curve of Annual Flow at Gulabgarh & Udaipur ...................................... 7.33 Figure 7.19: Double mass curve of annual flow at Benzwar and Udaipur ......................................... 7.33 Figure 7.20: Average 10-daily observed flows at Udaipur, Gulabgarh and Benzwar ................... 7.35 Figure 7.21: 10-daily observed flows at Udaipur and Benzwar for 1973-74 .................................... 7.36 Figure 7.22: 10-daily observed flows at Udaipur and Benzwar for 1974-75 .................................... 7.36 Figure 7.23: 10-daily observed flows at Udaipur and Benzwar for 1975-76 .................................... 7.37 Figure 7.24: 10-daily observed flows at Udaipur and Benzwar for 1976-77 .................................... 7.37 Figure 7.25: 10-daily observed flows at Udaipur and Benzwar for 1977-78 .................................... 7.38 Figure 7.26: 10-daily observed flows at Udaipur and Benzwar for 1978-79 .................................... 7.38 Figure 7.27: 10-daily observed flows at Udaipur and Benzwar for 1979-80 .................................... 7.39 Figure 7.28: 10-daily observed flows at Udaipur and Benzwar for 1980-81 .................................... 7.39 Figure 7.29: 10-daily observed flows at Udaipur and Benzwar for 1981-82 .................................... 7.40 Figure 7.30: 10-daily observed flows at Udaipur and Benzwar for 1982-83 .................................... 7.40 Figure 7.31: 10-daily observed flows at Udaipur and Benzwar for 1983-84 .................................... 7.41 Figure 7.32: 10-daily observed flows at Udaipur and Benzwar for 1984-85 .................................... 7.41 Figure 7.33: 10-daily observed flows at Udaipur and Benzwar for 1985-86 .................................... 7.42 Figure 7.34: 10-daily observed flows at Udaipur and Benzwar for 1986-87 ................................. 7.42 Figure 7.35: 10-daily observed flows at Udaipur and Benzwar for 1987-88 .................................... 7.43 Figure 7.36: 10-daily observed flows at Udaipur and Benzwar for 1988-89 .................................... 7.43 Figure 7.37: 10-daily observed flows at Udaipur and Benzwar for 1989-90 .................................... 7.44 Figure 7.38: 10-daily observed flows at Udaipur and Benzwar for 1990-91 .................................... 7.44 Figure 7.39: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1991-92 ............ 7.45 Figure 7.40: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1992-93 ............ 7.45 Figure 7.41: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1993-94 ............ 7.46 Figure 7.42: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1994-95 ............ 7.46 Figure 7.43: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1995-96 ............ 7.47 Figure 7.44: 10-daily observed flows at Udaipur, Gulabgarh & Benzwar for 1996-97 ............... 7.47 Figure 7.45: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1997-98 ............ 7.48 Figure 7.46: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1998-99 ............ 7.48 Figure 7.47: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1999-00 ............ 7.49 Figure 7.48: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 2000-01 ............ 7.49 Figure 7.49: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 2001-02 ............ 7.50 Figure 7.50: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 2002-03 ............ 7.50 Figure 7.51: 10-daily observed flows at Udaipur and Gulabgarh for 2003-04 ................................ 7.51 Figure 7.52: 10-daily observed flows at Udaipur and Gulabgarh for 2004-05 ................................ 7.51 Figure 7.53: 10-daily observed flows at Udaipur and Gulabgarh for 2005-06 ................................ 7.52



Figure 7.54: 10-daily observed flows at Udaipur and Gulabgarh for 2006-07 ................................ 7.52 Figure 7.55: 10-daily observed flows at Udaipur and Gulabgarh for 2007-08 ................................ 7.53 Figure 7.56: 10-daily observed flows at Udaipur and Gulabgarh for 2008-09 ................................ 7.53 Figure 7.57: 10-daily observed flows at Udaipur and Gulabgarh for 2009-10 ................................ 7.54 Figure 7.58: 10-daily observed flows at Udaipur and Gulabgarh for 2010-11 ................................ 7.54 Figure 7.59: 10-daily observed flows at Udaipur and Gulabgarh for 2011-12 ................................ 7.55 Figure 7.60: Comparison of derived series with observed data ............................................................ 7.60 Figure 7.61: 10-daily max, min and average computed flow at Dugar HEP ..................................... 7.63 Figure 7.62: Flow pattern in 50% and 90% dependable Year at Dugar HEP .................................... 7.63 Figure 7.63: Flow duration curve at Project site (10 daily basis) ........................................................... 7.66 Figure 7.64: Unit Hydrograph for Dugar H E project .................................................................................. 7.73 Figure 7.65: Temporal Distribution Curve of 24-hour Design Storm for Dugar HEP Site .......... 7.75 Figure 7.66: Design Flood (PMF) Hydrograph of Dugar HEP .................................................................. 7.78 Figure 7.67: Design Flood (SPF) Hydrograph of Dugar HEP.................................................................... 7.79 Figure 7.68: Time Series Graph, Udaipur Site ................................................................................................ 7.82 Figure 7.69: Time series graph, Udaipur site .................................................................................................. 7.84 Figure 7.70: Variation of discharge in the river ............................................................................................. 7.90 Figure 7.72: Time series graph, Udaipur site .................................................................................................. 7.93 Figure 7.72: Original Elevation-Area-Capacity curve at Dugar diversion site ................................ 7.101 Figure 7.73: Type of reservoir ............................................................................................................................. 7.102 Figure 8.1: Location Map of Dugar HEP ........................................................................................................... 8.11 Figure 8.2: MCT at Atholi/Gulabgarh, J&K. ..................................................................................................... 8.18 Figure 8.3: MBF as seen from Jammu-Srinagar highway (NH-44) near Nashri ............................... 8.18 Figure 8.4: The Major Tectonic Features in the Himalaya and The Great (M>8.0) Earthquakes in India ................................................................................................................................................................................... 8.20 Figure 8.5: Seismic and Neotectonic activity map of NW Himalayas .................................................. 8.21 Figure 8.6: Seismotectonic Domains of NW Himalayas ............................................................................ 8.22 Figure 8.7: Chenab River at the Dam site (U/S view) .................................................................................. 8.25 Figure 8.8: Rocky cliffs downstream of dam site on left bank (D/S view) ......................................... 8.26 Figure 8.9: Coarse Grained Biotite Gneiss ....................................................................................................... 8.28 Figure 8.10: Medium Grained Granitic Gneiss ............................................................................................... 8.29 Figure 8.11: Outcrop of Biotite Gneiss on Killar Road ............................................................................... 8.29 Figure 8.12: Granite Gneiss .................................................................................................................................... 8.30 Figure 8.13: Outcrop of Granite Gneiss on Chamba Road ....................................................................... 8.31 Figure 8.14: Banded Gneiss ................................................................................................................................... 8.31 Figure 8.15: Outcrop of Banded Gneiss ........................................................................................................... 8.32 Figure 8.16: Outcrop of Augen Gneiss ............................................................................................................. 8.32 Figure 8.17: Micaceous Quartzite ....................................................................................................................... 8.33 Figure 8.18: Outcrop of Micaceous Quartzite at the end of Punto Road .......................................... 8.34 Figure 8.19: Biotite Schist ....................................................................................................................................... 8.35



Figure 8.20: Outcrop of Biotite Schist in Road Cut Upstream of Mahal Nala .................................. 8.35 Figure 8.21: A major discordant pegmatite intrusive in Killar road section at KRD 4.7 ............... 8.36 Figure 8.22: Pegmatite ............................................................................................................................................ 8.37 Figure 8.23: Pegmatite exposure on right bank at dam site ................................................................... 8.37 Figure 8.24: Local structural terrace type of tight fold .............................................................................. 8.38 Figure 8.25: Major shear downstream of the dam site on left bank ...................................................... 8.41 Figure 8.26: Sheared contact of biotite gneiss and pegmatite on right bank ..................................... 8.42 Figure 8.27: Location of Project Alternatives ................................................................................................... 8.42 Figure 8.28: RQD vs. Core recovery correlations of DH-01 hole ........................................................... 8.50 Figure 8.29: RQD vs. Core recovery correlations of DH-03 hole.............................................................. 8.51 Figure 8.30: Drilling platform of river centre drill hole DH-06 ............................................................... 8.52 Figure 8.31: Exploratory drift DL-02 .................................................................................................................. 8.59 Figure 8.32: Exploratory drift DR-01. .................................................................................................................. 8.60 Figure 8.33: Exploratory Drift DR-02 ................................................................................................................. 8.61 Figure 8.34: Exploratory drift DR-02. From clockwise, shear seam along foliations, plant roots, shear seams, and iron staining/soil leaching along open joints ............................................................. 8.62 Figure 8.35: In Progress Power House Drift (PHD) ...................................................................................... 8.63 Figure 8.36: From clockwise a) view of rock core samples after UCS with Modulus b) Core after Tensile Strength c) Core samples after Point Load Test d) Samples after Modulus of Elasticity (Dry Condition). ...................................................................................................................................................................... 8.68 Figure 8.37: Plate Load Test Assembly-In-situ Tests .................................................................................. 8.69 Figure 8.38: Sheared test blocks, Concrete to Rock & Rock to Rock (Block Shear Test) ............ 8.70 Figure 8.39: Right Abutment .................................................................................................................................. 8.74 Figure 8.40: Stereographic projection of Right Abut. discontinuities, cut slope and fiction circle. ............................................................................................................................................................................................. 8.74 Figure 8.41: Right b showing blocky nature of exposed litho-units & Geological investigation details. ............................................................................................................................................................................... 8.75 Figure 8.42: Approximate Shear seams location (red dash-Pg & Gg (S1), blue dash-Pg-Sc-Gg (S2)) ................................................................................................................................................................................... 8.78 Figure 8.43: Left Abutment .................................................................................................................................... 8.79 Figure 8.44: Stereographic projection of left Abut. discontinuity, cut slope and fiction circle. .... 8.80 Figure 8.45: Approx. Location of D/s Cofferdam. .......................................................................................... 8.86 Figure 8.46: Approx. Location of U/s Cofferdam. ........................................................................................... 8.87 Figure 8.47: Stereographic Projection, Diversion Tunnel ......................................................................... 8.88 Figure 8.48: Diversion Tunnel, Inlet Portal ...................................................................................................... 8.89 Figure 8.49: RQD Vs. Core Recovery is drill hole DH-16 ........................................................................... 8.89 Figure 8.50: Intake Portal Area ............................................................................................................................. 8.91 Figure 8.51: RQD Vs. Core Recovery in DH-19 drill Hole.......................................................................... 8.92 Figure 8.52: Schematic Sketch showing L-Section of Pressure Tunnel/Shaft .................................. 8.93 Figure 8.53: Stereonet showing joints and alignment of tunnel ........................................................... 8.94 Figure 8.54: Layout Power House Complex ................................................................................................... 8.97



Figure 8.55: Stereonet Showing Discontinuity Pattern .............................................................................. 8.98 Figure 8.56: Tailrace Tunnels Outfall Area .................................................................................................... 8.102 Figure 8.57: MAT Portal Location ..................................................................................................................... 8.105 Figure 8.58: Slide zone just downstream of the Mahalu road bridge ................................................. 8.107 Figure 8.59: Rocky valley faces in reservoir area. ......................................................................................... 8.107 Figure 8.60: Exposed V-shaped valley, reservoir area .............................................................................. 8.109 Figure 8.61: Stereoplot of the discontinuities exposed along the Reservoir Rim ....................... 8.112 Figure 8.62: Right and left bank slope of reservoir area ....................................................................... 8.113 Figure 8.63: Chart for Stability Analysis of Circular Failure .................................................................... 8.114 Figure 8.64: Left Bank Slope, stability analysis (for detail refer geol dwg, volume IIIB) ............ 8.115 Figure 8.65: Material properties derived from back analysis .................................................................. 8.117 Figure 8.66: Factor of Safety of cut slope in normal loading condition .............................................. 8.117 Figure 8.67: Factor of Safety of cut slope in seismic loading condition .......................................... 8.118 Figure 10.1: Pattern of Flow in 90% & 50% Dependable Years ............................................................ 10.9 Figure 10.2: Long Term Flow Duration Curve for Ten Daily Available Discharges from 1974-75 to 2011-12 (38 years) ............................................................................................................................................... 10.10 Figure 10.3: Area-Capacity Elevation Curve for Dugar Reservoir ........................................................ 10.12 Figure 10.4: Tail Water Rating Curve ............................................................................................................... 10.13 Figure 10.5: Daily Load Curves in Northern Region-Representative week in December 2004 ........................................................................................................................................................................................... 10.15 Figure 10.6: Annual Energy vs. Installed Capacity ..................................................................................... 10.20 Figure 10.7: Incremental Energy/ Per MW Increase in Installed Capacity ....................................... 10.20 Figure 10.8: Annual Plant Load Factor vs. Installed Capacity ................................................................ 10.21 Figure 10.9: Rating Curve at TRT outlet of Auxiliary Units ..................................................................... 10.23 Figure 11.1: Area-Elevation Capacity Curve for Dugar Reservoir .......................................................... 11.6 Figure 11.2: Rating Curve at 100 m downstream of Dam ........................................................................ 11.8 Figure 11.3: Upper Spillway – Discharge Capacity vs. Reservoir Level .............................................. 11.11 Figure 11.5: Lower Level Spillway – Discharge Capacity vs. Reservoir Level .................................. 11.13 Figure 11.5: Rating Curve at Diversion Tunnel Outlet ............................................................................. 11.16 Figure 11.6: Optimisation Curve for Diversion Tunnel Diameter ........................................................ 11.20



LIST OF ANNEXES

Annex 10.1: Average 10-daily flows at Dugar Dam Site (m3/s) on River Chenab (1974-75 to 2011-12) ........................................................................................................................................................................ 10.27 Annex 10.2: Unrestricted Power for Hydrological Years from 1974-75 to 2011-12 ................... 10.29 Annex 10.3: Unrestricted Energy for Hydrological Years from 1974-75 to 2011-12 .................. 10.31 Annex 10.4: Utilization of Inflows during 90% Dependable Year ....................................................... 10.33 Annex 10.5: Parameters for Head Loss Calculations of Main Plant ................................................... 10.34 Annex 10.6: Head Loss/Net Head Computations for Different Installed Capacity ...................... 10.35 Annex 10.7: Energy Calculations in 90% Dependable Year for Installed Capacity as 380 MW ........................................................................................................................................................................................... 10.39 Annex 10.8: Energy Calculations in 50% Dependable Year for Installed Capacity as 380 MW ........................................................................................................................................................................................... 10.40 Annex 10.9: Plant Operability during Monsoon ......................................................................................... 10.41 Annex 10.10: Plant Operability during Lean Season ................................................................................ 10.42 Annex 10.11: Plant Operability during Lean Season considering Auxiliary Units ........................ 10.44 Annex 10.12: Available Peaking Time during Lean Season in 90% Dependable Year ............... 10.45 Annex 10.13: Parameters for Head Loss Calculations of Auxiliary Units ......................................... 10.46 Annex 10.14: Head Loss Computations for Auxiliary Units ................................................................... 10.47 Annex 10.15: Energy Calculations for Auxiliary Units .............................................................................. 10.49

EXECUTIVE SUMMARY

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Executive Summary Dugar Hydro Electric Project 2


TABLE OF CONTENT

EXECUTIVE SUMMARY ........................................................................... 3

PROJECT LOCATION ............................................................................................................................. 3

ABOUT THE PROJECT ........................................................................................................................... 4

CLIMATE 5

HYDROLOGY ........................................................................................................................................... 5

INDUS WATER TREATY ........................................................................................................................ 7

GEOLOGY 7

PROJECT FEATURES .............................................................................................................................. 8

POWER PLANT ...................................................................................................................................... 10

DESIGN ENERGY .................................................................................................................................. 11

INFRASTRUCTURE WORKS .............................................................................................................. 11

© The Copyright remains with AF-Consult Switzerland Ltd.



EXECUTIVE SUMMARY

PROJECT LOCATION

Dugar HEP is located on Chenab River near Killar village in Chamba district of Himachal Pradesh. The latitude and longitude of project site are N 33° 07’ 05” and E 76° 21’ 20.7” respectively. The Dugar project site lies between the Sachkhas HEP (267 MW) at its upstream and the Kirthai-I HEP (390 MW) at downstream. The project site is located near Luj village which is about 10 km from the nearest town, Killar.

The nearest rail heads are the railway stations Udhampur and Pathankot. Udhampur Railway Station is in Udhampur city in the state of Jammu & Kashmir, while Pathankot Railway Station is in Pathankot city in the state of Punjab. The distance from Udampur to project site is about 270 km.

The nearest airports are Kullu-Manali and Jammu. The distance from Kullu to project site is about 279 km and from Jammu to project site is about 332 km.

The location of the project is shown in Figure 1.

Figure 1: Location Plan of Dugar HEP



ABOUT THE PROJECT

This greenfield project has been awarded to the consortium “Tata Power Company Ltd. and SN Power Holding Singapore Pte. Ltd.” (Owner) in May 2011, by Directorate of Energy - Government of Himachal Pradesh on Build-Own-Operate-Transfer (BOOT) basis for a period of 40 Years from Commercial Operation Date. To implement the project, the Owner has constituted a Special Purpose Vehicle (SPV) by the name of M/s Dugar Hydro Power Limited (DHPL).

The Dugar Hydro Electric Project (449 MW) is envisaged as a run-of-river scheme for utilizing the flows of Chenab River to harness the head created by constructing a 128 m high (from deepest foundation) dam near Luj village with FRL of EL 2114.00 m asl and the proposed underground power house located on the left bank of Chenab River just downstream of dam. It is a medium head scheme with rated net head of 91.21 m having Full Reservoir Level (FRL) and Minimum Draw Down Level (MDDL) as 2114.00 m asl and 2102.35 m asl respectively. It is essentially a run-of-river scheme with diurnal storage for generation of electricity. The project comprises of a 128 m high concrete gravity dam (from deepest foundation level), 2 Nos. underground circular pressure shafts of length 270 m and 307 m. Each pressure shaft is bifurcated upstream of the unit valves. An underground power house is envisaged followed by a tailrace surge chamber and two tail race tunnels of finished diameter as 7.8 m. The tail race tunnels, located on the left bank of the Chenab River, are discharging back into Chenab River at a distance of about 725 m downstream of dam axis with normal tail water level as 2015.00 m asl (under normal operating condition) and minimum tail water level as 2012.26 m asl.

To harness the environmental flow during lean season and non-lean non-monsoon season three units each of 23 MW are housed in the power house cavern. Therefore the total capacity of plant shall be 449 MW (380 +69 MW).

The main components of the project are:

• A 128 m high concrete gravity dam (from the deepest foundation level) located on River Chenab at Latitude N 33° 07’ 05” and longitude E 76° 21’ 20.7”.

• Two numbers main intakes and one intake for auxiliary power house located at the left bank.

• Two numbers main pressure shafts and one pressure shaft for auxiliary power house.

• Underground cavern housing four number main units of 95 MW each and three units of 23 MW each for auxiliary power house.

• Transformer Cavern located upstream of power house cavern.



• Four number main TRTs having Surge Chamber at the upstream end and one TRT for auxiliary power house discharging downstream of dam.

To facilitate the construction and operation of the project components, suitable adits and access roads have been proposed.

CLIMATE

The sources of runoff in the Chenab basin are both rain and snowmelt. The flows during March to June are largely contributed by snowmelt, although pre-monsoon rainfall also contributes to a certain extent. From July to September, the river carries high discharges due to monsoon precipitation combined with snow melt. The minimum flows occur during the winter months of December, January and February as in all snow fed Himalayan Rivers.

DHPL has installed an Automatic Weather Station near the project site. Average maximum temperature at diversion site ranges from -2.50C in January to 20.20C in July.

HYDROLOGY

The catchment area of Chenab River upto Dugar diversion site is estimated as 7,823 km2 from the SRTM data. With the permanent snowline at 4500 masl, the snow fed catchment is 4,458 km2 and the remaining 3,365 km2 is rain fed.

For the various data consistency checks it is found that the discharge data of Udaipur G&D site is consistent and reliable. The proposed Dugar HE Project is located downstream of Udaipur Gauge & Discharge site. The catchment area ratio of Dugar HEP (7823 Km2) and Udaipur G&D site (5910 Km2) is 1.32. The observed 10-daily flow at Udaipur for the period 1974-75 to 2011-12 has been considered for the computation of long-term flow series at Dugar HEP. The 10-daily observed flow series at Udaipur G&D of CWC for the period 1974-75 to 2011-12 has been utilized for the present study and transferred to Dugar diversion site in catchment area proportion. The flow series of Dugar HEP has been conveyed by Central Electricity Authority (CEA) vide their letter no. 2/HP/52/CEA/2013-PAC/6826-28 dated 12th December 2013.

The 90% and 50% dependable years works out to 1993-94 and 1980-81 respectively.

The total available flows at the diversion site are plotted as flow duration curve in Figure 2 and also given in Table 1.



Table 1: Results of Flow Duration Curve

Exceedance (%) Discharge (m3/s) Exceedance (%) Discharge (m3/s)

5 1050 55 106

10 897 60 95

15 771 65 87

20 645 70 81

25 511 75 75

30 381 80 68

35 267 85 60

40 198 90 52

45 156 95 44

50 127 100 29

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100

Disc

harg

e (m

3 /s)

Exceedance (%)

Figure 2: Flow Duration Curve for Ten Daily Available Discharges at Dugar HEP Dam Site (1974-75 to 2011-12)

The design floods for the project are worked out from hydro-meteorological approach and frequency approach. The following design floods for Dugar HEP has been conveyed by Central Electricity Authority (CEA) vide their letter no. 2/HP/52/CEA/2013-PAC/868-70 dated 5th March 2014.

Probable Maximum Flood (PMF) 9,425 m3/s

25 Year return period (~Q25) monsoon flow 2,700 m3/s



INDUS WATER TREATY

Dugar HEP lies on the Chenab Main River in district Chamba, Himachal Pradesh and is governed by the relevant provisions of “Indus Water Treaty 1960” (IWT) signed between India and Pakistan. The maximum pondage as per IWT ”shall not exceed twice the Pondage required for Firm Power“. Central Electricity Authority (CEA) vide their letter no. 2/HP/52/CEA/2013-PAC/163-64 dated 9th January 2014 has conveyed the maximum pondage as 19.58 Mm3. The live storage has been kept as 16.57 Mm3 which is less than the maximum pondage as per IWT. The reservoir area-capacity curve is given in Figure 3 below.

2015

2035

2055

2075

2095

2115

2135020406080

2015

2035

2055

2075

2095

2115

2135

0 40 80 120 160 200 240

Elev

atio

n (m

asl)

Volume (MCM)

Elev

atio

n (m

asl)

Area (Ha)

Area-Elevation Capacity-Elevation

Figure 3: Reservoir Area-Capacity Curve

GEOLOGY

Regional Geology

The Dugar HEP is located within the Central Crystallines represented by the Vaikrita Group of rocks. Regionally, the area around the project comprises litho-stratigraphic sequence from Proterozoic to the Quaternary in age including Salkhala Group and Chamba, Manjir, Katarigali, Bhaderwah and Dul Formations. The regional litho-stratigraphic sequence has been summarized in Table.1 The rock formations in the immediate vicinity of the project area include granitoids belonging to the Rohtang Crystalline Complex towards north and east, and Batal Formation of Haimanta Group further north and towards south.



Project Geology

The project area lies in the zone of Central Crystallines belonging to Vaikrita Group and hence dominated by a variety of gneissic rocks. Large areas on right bank are under the colluvium cover for which rock outcrops along the roads are rather infrequent and limited in extent. Extensive rock outcrops are found exposed along Punto road. In general, biotite gneiss is the most dominant rock type in the mapped area. The strata have been intruded by a number of pegmatite and granite bodies which are both concordant as well as discordant. In addition to the biotite gneisses, beds of banded gneiss, augen gneiss, granite gneiss, micaceous quartzites and mica schist are found in the reservoir area.

In general, the broad lithological sequence in the mapped area from upstream to downstream comprises coarse grained biotite gneiss at the tail end of reservoir, followed by fine grained, dark micaceous quartzite, biotite schist, micaceous quartzite and finally medium to coarse grained biotite gneiss that continues upto and beyond dam site. The biotite gneiss towards downstream is the most prominent lithological unit occupying almost downstream half of the combined area of the project and reservoir.

Dam

The River valley at the proposed dam site is characterized by steep rocky cliffs on both banks. The cliff is developed mainly within massive bed of pegmatite which is found exposed from river bed level to the top of the cliff on right bank and from River bed level to the portal of the upper drift on left bank. Biotite gneiss is found exposed above this pegmatite bed on both banks at dam site. The biotite gneiss is also found as an approximately 9 m thick xenolithic bed on the right bank and in view of gentler slopes on the banks is found widely exposed.

Pressure Tunnels & Power House Complex

Almost the entire layout of the water conductor system and the powerhouse complex lies within thickly forested area developed over a gentle slope & confined between rock cliffs both towards the River as well as mountain side. A part of this forested area around the dam axis is particularly flatter where a rock terrace could be expected. By virtue of the thick forest cover and the consequent inaccessibility, the geological details are limited, but, based on the well exposed geological setting in the dam abutment area, it is interpreted that the layout lies within biotite gneisses with overwhelming cover of colluvium. The traverses within the accessible zones of the forest reveal the presence of thick overburden.

PROJECT FEATURES

After examining possible alternatives optimal layout has been considered as shown in attached drawings. The proposed Dugar HEP comprises of the following structures:



Concrete Gravity Dam: The dam is located near Luj village. The waterway is provided with seven orifice spillways with crest elevation 2074 m asl and two upper level overflow spillway with crest level 2102.30 m asl.

Main features include:

- Dam height from deepest foundation level 128.0 m

- Top width of dam 214.8 m

- Design Flood (PMF) 9,425 m3/s

- Maximum Reservoir Level (MRL) 2114.00 m asl

- Full Reservoir Level (FRL) 2114.00 m asl

- Minimum Draw-Down Level (MDDL) 2102.35 m asl

- Energy Dissipation Flip bucket

Pondage: Since Dugar HEP lies on Chenab River, therefore it is governed by Indus Water Treaty (IWT). The pondage i.e. live storage of the project has been worked out as per the prevailing provisions of IWT. Live storage of 16.57 x 106 m3 has been provided between FRL of 2114.00 m asl and MDDL of 2102.35 m asl. The gross storage at FRL is 61.58 x 106 m3 and dead storage at MDDL is 45.01 x 106 m3. The total extent of reservoir is about 12.2 km from the dam axis.

Intake: The intake structures are located at the left bank of the Chenab River about 25 m upstream of the dam axis. To guarantee the submerging criteria with respect to the MDDL of 2102.35 m asl, the invert level is fixed at an elevation of 2084.65 m asl. The main intake structure comprises of two segments and each segment is designed for a design discharge of 229.58 m3/s. Intake gates, trash rack and trash rack cleaning machine have been provided.

One intake for auxiliary plant is also provided along with the main intake structure with the design discharge of 87.25 m3/s.

Pressure Shafts/Tunnels (HRT): Two underground circular pressure shafts of length 260 m and 290 m are proposed to convey water from reservoir two power house. The upper horizontal portion and the vertical shaft upto lower bend are proposed to be concrete lined. The lower bend of vertical shaft and the lower pressure tunnel are proposed to be steel lined. The internal diameter of concrete lined and steel lined pressure shaft is proposed as 8.1 m and 6.7 m respectively. Each pressure shaft is bifurcated upstream of the unit valves. The internal diameter of bifurcated pressure shaft is 4.75 m.

For three auxiliary units one combined pressure tunnel/shaft if proposed bifurcated just upstream of MIV. The total length of pressure tunnel/shaft is about 229 m. The upper horizontal portion and the vertical shaft upto lower bend are proposed to be concrete lined. The lower bend of vertical shaft and the lower pressure tunnel are proposed to be steel lined. The internal diameter of concrete lined and steel lined pressure shaft is proposed as 5.6 m and 4.1 m respectively. The internal diameter of trifurcated pressure shaft is 2.4 m.



Power House Cavern: An underground power house is foreseen on the left bank of Chenab River just downstream of the dam. Power house will accommodate four units of 95 MW each and three units of 23 MW each. The overall dimensions of power house cavern are 173.0 m (L) x 22.5 m (W) x 44.5 m (H). The turbine setting elevation for units of 95 MW is 2002.50 m asl and for 23 MW units it is 2006.50 m asl. Access to power house is through 665 m long Main Access Tunnel (MAT).

Transformer Cavern: The transformer cavern is located 40 m upstream of power house cavern. In total fourteen transformers, thirteen single phase transformers of 43 MVA each for the main power house and three three phase transformer of 13.5 MVA for the auxiliary plant will be housed in an underground cavern. The overall dimensions of transformer cavern are 155 m (L) x 14.0 m (W) x 20.5 m (H). Transformer cavern will house the 400kV GIS.

Surge & Draft Tube Gate Cavern: The underground surge cavern is located approximately 40 m downstream of the powerhouse cavern. For inspection and maintenance of the turbines, four draft tube gates are provided, within surge chamber, which will be operated from the deck at EL 2036.00 m asl. The dimensions of the each compartment are 28 m (L) x 22 m (W) x 37 m (H). The cavern comprises of four individual surge chamber of finished size 28 m (L) x 22 m (W).

Tail Race Tunnels: Four numbers unit tailrace tunnels of finished diameter 5.7 m are provided starting from the downstream of power house upto downstream surge chamber. The length of the each unit tailrace tunnel is 87.4 m. After the downstream surge chamber two unit tailrace tunnels are merged into one tailrace tunnel of 8.1 m diameter. Lengths of the two tailrace tunnels of 8.1 m diameter are 385 m and 408 m for right and left tunnel respectively. Tailrace tunnels are fully concrete-lined. Finished shape of tailrace tunnels is circular whereas the excavated profile in modified horseshoe type. At the downstream end tailrace tunnel of 8.1 m diameter is again bifurcated to two D- shape tunnels of diameter 5.7 m to reduce the size of TRT outfall structure. The tail race tunnels, located on the left bank of the Chenab River, are discharging back into Chenab River at a distance of about 725 m downstream of dam axis.

POWER PLANT

Central Electricity Authority (CEA) has conveyed the capacity of Dugar HEP as 449 MW (380 MW + 69 MW).

The generating equipment, the group of four turbines and generators each unit of 95 MW and three units of 23 MW will be of vertical shaft type accommodated in the machine hall. The centre to centre spacing of Turbine-generator units is kept as 18.5 m for 95 MW units. The lengths of Unit-1 to Unit-4 bays are kept as 18.50 m. The Erection Bay will be 26 m long and control block will be 20 m long proposed longitudinally adjacent to Unit # 7.



DESIGN ENERGY

In order to maximize the benefits of the project the optimization of installed capacity has been carried out by studying incremental energy with increase in installed capacity for 90% dependable year and takes into account the following features:

a. The hydraulic average gross head has been considered with an average reservoir level corresponding to level as 2/3(FRL-MDDL) + MDDL and considering normal Tail Water Level.

b. All major head losses which include friction loss in pressure shaft/tunnel and tailrace tunnel are determined for each installed capacity. In addition to major losses, the minor losses are also considered.

c. The combined efficiency factor for the electro-mechanical equipment is taken as 92.5%

d. The design energy for the project evaluation is considered as annual energy available in a 90% dependable year with installed capacity restricted to 95%.

The reservoir created by the dam located near the Luj village will operate between FRL 2114.00 m asl and MDDL 2102.35 m asl. The installed capacity of the main power house will be 380 MW (4 x 95 MW). The rated head of the scheme is 91.21 m and the nominal discharge is 114.79 m3/s for each unit of 95 MW. Plant load factor for 90% and 50% dependable years are 40.5% and 46.9% respectively. The design energy during 90% dependable year at 95% plant availability is 1315 GWh. The rated head for auxiliary power plant is 89.57 m and the rated discharge is 29.08 m3/s for each unit of 23 MW. The auxiliary power plant will have an installed capacity of 69 MW. The design energy at 95% plant availability works out to be 302.4 GWh. The total design energy from main plant as well as auxiliary plant is 1617.4 GWh (1315.0 + 302.4 GWh).

INFRASTRUCTURE WORKS

Since the project components are on the left bank of Chenab River, a permanent bridge is proposed downstream of the dam to approach the left bank and power house complex construction adits through this bridge. The road to this bridge (about 4.5 km) is planned from the existing road at right bank which is at higher elevation. One more permanent bridge is proposed to access the MAT and TRT gate operation chamber. One temporary bridge is proposed upstream of the dam axis to access the intake structure.

In addition to the permanent access roads, temporary access roads to DT inlet, DT outlet, u/s and d/s cofferdams etc., strengthening and widening of existing roads, bridges and culverts are also foreseen. One new permanent bridge is foreseen in place of the existing Shukrali Bridge (connects Killar to Chamba via Sach Pass) which is coming under submergence.

CHAPTER 1: INTRODUCTION

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Introduction Dugar Hydro Electric Project 1.1


TABLE OF CONTENT

1 INTRODUCTION ......................................................................... 1.2

1.1 GENERAL .................................................................................................................................. 1.2

1.2 PROJECT LOCATION & ACCESS ...................................................................................... 1.2

1.3 CLIMATIC CONDITION........................................................................................................ 1.3

1.4 TOPOGRAPHY & PHYSIOGRAPHY ................................................................................. 1.4

1.5 GEOLOGY ................................................................................................................................. 1.4 1.5.1 Regional Geology ................................................................................................................. 1.4 1.5.2 Project Geology ..................................................................................................................... 1.4

1.6 HISTORICAL BACKGROUND OF THE PROJECT .......................................................... 1.5 1.6.1 Pre-Feasibility Study ............................................................................................................ 1.5 1.6.2 Detailed Project Report ...................................................................................................... 1.6

1.7 NEED OF THE PROJECT....................................................................................................... 1.7

1.8 ALTERNATIVE STUDY .......................................................................................................... 1.7

1.9 INTER STATE, INTERNATIONAL OR DEFENCE ASPECT ........................................... 1.8

LIST OF FIGURES

Figure 1.1: Location of The Project .................................................................................................................... 1.3

© The Copyright remains with AF- Consult Switzerland Ltd.



1 INTRODUCTION

1.1 GENERAL

The state of Himachal Pradesh has vast Hydro Power potential. The main rivers that flow through Himachal Pradesh are Satluj, Beas, Ravi and Chenab. The Chenab River, also known as Chandra Bhaga River in its upper reaches is formed by the confluence of two rivers viz. Chandra and Bhaga at Tandi near Keylong in Lahaul & Spiti district of Himachal Pradesh. Chenab River enters Pangi valley of Chamba district in Himachal Pradesh near Bhujind and leaves the district at Sansari Nala to enter Podar valley of Kashmir. Dugar Hydro Electric Project is in Pangi valley on Chenab River and is a run-of-river scheme.

1.2 PROJECT LOCATION & ACCESS




The location of the project is shown in Figure 1.1.



Figure 1.1: Location of The Project

1.3 CLIMATIC CONDITION

The sources of runoff in the Chenab basin are both rain and snowmelt. The flows during March to June are largely contributed by snowmelt, although pre-monsoon rainfall also contributes to a certain extent. From July to September, the river carries high discharges due to monsoon precipitation combined with snow melt. The minimum flows occur during the winter months of December, January and February as in all snow fed Himalayan Rivers.

Dugar Hydro Power Ltd. (DHPL) has installed an Automatic Weather Station near the project site. Average maximum temperature at diversion site ranges from -2.5 0C in January to 20.2 0C in July.



1.4 TOPOGRAPHY & PHYSIOGRAPHY

The Chenab, a major drainage basin, lies between the Pir Panjal Range towards south and the Great Himalayan Range towards north. The terrain is essentially mountainous and the landscape has been shaped in the Quaternary period by glacial and fluvial activities. It is characterized by lofty mountains and deep valleys with gradual blending of different forms of relief and slopes. Over the State of Himachal Pradesh, elevations above mean sea level vary from as low as 300 m in the south, adjacent to the great plain of Indus-Ganga Alluvium, to as high as 7000 m at the peaks of Great Himalayan Range in Kinnaur District bordering Tibet.

There are plentiful of grazing lands on the upper reaches of high mountains. A number of meadows and pastures on the uplands are well known. The region is full of vegetation with dominance of conifers. The local population have extended their settlements in these thick forests at high reaches.

Rocks are strongly folded at certain places and are mainly composed of granite, gneiss, schist, quartzite and phyllite. Some hot springs along river course have been observed in the area from where the water is emerging from the earth in its natural form.

1.5 GEOLOGY

1.5.1 Regional Geology

The Dugar HEP is located within the Central Crystallines represented by the Vaikrita Group of rocks. Regionally, the area around the project comprises litho-stratigraphic sequence from Proterozoic to the Quaternary in age including Salkhala Group and Chamba, Manjir, Katarigali, Bhaderwah and Dul Formations. The regional litho-stratigraphic sequence has been summarized in Table.1 The rock formations in the immediate vicinity of the project area include granitoids belonging to the Rohtang Crystalline Complex towards north and east, and Batal Formation of Haimanta Group further north and towards south.

1.5.2 Project Geology

The project area lies in the zone of Central Crystallines belonging to Vaikrita Group and hence dominated by a variety of gneissic rocks. Large areas on right bank are under the colluvium cover for which rock outcrops along the roads are rather infrequent and limited in extent. Extensive rock outcrops are found exposed along Punto road. In general, biotite gneiss is the most dominant rock type in the mapped area. The strata have been intruded by a number of pegmatite and granite bodies which are both concordant as well as discordant. In addition to the biotite gneisses, beds of banded gneiss, augen gneiss, granite gneiss, micaceous quartzites and mica schist are found in the reservoir area.



In general, the broad lithological sequence in the mapped area from upstream to downstream comprises coarse grained biotite gneiss at the tail end of reservoir, followed by fine grained, dark micaceous quartzite, biotite schist, micaceous quartzite and finally medium to coarse grained biotite gneiss that continues upto and beyond dam site. The biotite gneiss towards downstream is the most prominent lithological unit occupying almost downstream half of the combined area of the project and reservoir

1.5.2.1 Dam

The River valley at the proposed dam site is characterized by steep rocky cliffs on both banks. The cliff is developed mainly within massive bed of pegmatite which is found exposed from river bed level to the top of the cliff on right bank and from River bed level to the portal of the upper drift on left bank. Biotite gneiss is found exposed above this pegmatite bed on both banks at dam site. The biotite gneiss is also found as an approximately 9m thick xenolithic bed on the right bank and in view of gentler slopes on the banks is found widely exposed.

1.5.2.2 Pressure Tunnels & Power House Complex

Almost the entire layout of the water conductor system and the powerhouse complex lies within thickly forested area developed over a gentle slope & confined between rock cliffs both towards the River as well as mountain side. A part of this forested area around the dam axis is particularly flatter where a rock terrace could be expected. By virtue of the thick forest cover and the consequent inaccessibility, the geological details are limited, but, based on the well exposed geological setting in the dam abutment area, it is interpreted that the layout lies within biotite gneisses with overwhelming cover of colluvium. The traverses within the accessible zones of the forest reveal the presence of thick overburden.

1.6 HISTORICAL BACKGROUND OF THE PROJECT

1.6.1 Pre-Feasibility Study

This greenfield project has been awarded to the consortium “Tata Power Company Ltd. and SN Power Holding Singapore Pte. Ltd.” (Owner) in May 2011, by Directorate of Energy - Government of Himachal Pradesh on Build-Own-Operate-Transfer (BOOT) basis for a period of 40 Years from Commercial Operation Date on successfully bidding the highest amount of additional free power to the state of Himachal Pradesh. To implement the project, the Owner has constituted a Special Purpose Vehicle (SPV) by the name of M/s Dugar Hydro Power Limited (DHPL).

The pre-feasibility study of the Dugar HEP was carried out by DHPL. As per pre-feasibility study, Dugar HEP a run-of-river scheme located in the District Chamba of Himachal Pradesh, envisaged construction of a concrete gravity dam 97 m high (from river bed level) across Chenab River near Luj village (33° 07’ 10.3”N, 76° 19’



35.7”E), four intakes followed by four HRTs of about 150 m long and 6.5 m finished diameter, four Nos. steel lined pressure shafts about 152 m long & 5.5 m internal diameter, an underground powerhouse (150 m (L) x 23 m (B) x 46 m (H)) near dam axis on the left bank of Chenab River to accommodate 4 units of 95 MW each and a concrete lined horse shoe shaped tail race tunnel of about 350 m length and 12.0 m finished diameter for discharging the water back into Chenab River. An underground tailrace surge chamber (150 m (L) x 14 m (B) x 45 m (H)) is provided downstream of the power house cavern and transformer cavern is accommodated above the surge chamber.

Rated head and rated discharge were estimated as 93 m and 113 m3/s respectively. With FRL at 2105 m asl and MDDL at 2096 m asl, 11 Mm3 live diurnal storage was provided. Gross head is considered as 99 m with FRL as 2105 m asl and normal TWL as 2006 m asl. In PFR the annual energy generation was estimated as 1552 GWh for 90% dependable year.

1.6.2 Detailed Project Report

The stage-I clearance of the project was obtained by DHPL from Ministry of Environment & Forest (MoEF), Govt. of India in the month of December, 2012 as per layout and project features envisaged in PFR.

In November 2012 AF Consult Switzerland Ltd. (AFC) was entrusted with the work of detailed investigations and preparation of the Detailed Project Report for Dugar HEP by DHPL. Subsequently the investigations are carried out by AFC and the Detailed Project Report is prepared.

The Dugar Hydro Electric Project (449 MW) is envisaged as a run-of-river scheme for utilizing the flows of Chenab River to harness the head created by constructing a 128 m high (from deepest foundation) dam near Luj village with FRL of EL 2114.00 m asl and the proposed underground power house located on the left bank of Chenab River just downstream of dam. It is a medium head scheme with rated net head of 91.21 m having Full Reservoir Level (FRL) and Minimum Draw Down Level (MDDL) as 2114.00 m asl and 2102.35 m asl respectively. It is essentially a run-of-river scheme with diurnal storage for generation of electricity. The project comprises of a 128 m high concrete gravity dam (from deepest foundation level), 2 Nos. underground circular pressure shafts of length 270 m and 307 m. Each pressure shaft is bifurcated upstream of the unit valves. An underground power house is envisaged followed by a tailrace surge chamber and two tail race tunnels of finished diameter as 8.1 m. The tail race tunnels, located on the left bank of the Chenab River, are discharging back into Chenab River at a distance of about 725 m downstream of dam axis with normal tail water level as 2015.00 m asl (under normal operating condition) and minimum tail water level as 2012.26 m asl.



To harness the environmental flow during lean season, non-lean non-monsoon season and monsoon season three units each of 23 MW are housed in the power house cavern. Therefore the total capacity of plant shall be 449 MW (380 +69 MW).

1.7 NEED OF THE PROJECT

India has been facing electricity shortages in spite of appreciable growth in electricity generation. The demand for electrical energy has been growing at a much faster rate and is expected to increase further to match with the projected growth of Indian economy. The per capita electricity consumption which was 18.17 kWh during 1950 has increased to 733.54 kWh during the year 2008-09.

Keeping in view the future electricity demand central government and the state governments has planned to increase the energy generation in their annual and five year plans.

As per annual plan 2008-09 of Government of Himachal Pradesh the total identified hydro potential is 20415.62 MW. Out of this 2251.0 MW is in Chenab basin. All the available hydro potential of Chenab Basin is unexploited so far. In the annual plan 2008-09, 24 projects have been identified for allotment to IPPs, out of 24 project, 14 projects are in Chenab basin. Dugar HEP is of these 14 projects identified by Government of Himachal Pradesh for allotment to IPP.

Dugar HEP also fits well in the development of Chenab basin as the project located between the Sach Khas HEP on the upstream and Kirthai-I HEP on the downstream utilizes the head available in between upstream and downstream project boundaries.

The implementation of the proposed Dugar HEP (449 MW), will contribute to meeting the power and energy demand in the Northern Region which comes under the purview of Northern Eastern Western and North-Eastern (NEWNE) grid and will displace electricity that would otherwise have to be produced through the construction of fossil fuel based thermal power plants.

1.8 ALTERNATIVE STUDY

Four different dam sites have been taken into consideration during Alternative Study. Dam axes have been selected within the concession limits of Dugar HEP defined in between FRL as 2105.0 m asl and normal tail water level as 2006.0 m asl. The site of Alternative-I is located at km 5+510 (starting from the upstream concession limit). Alternative-II is situated approximately 1.06 km downstream of the bridge (Shukrali Bridge) of the Sach-Pass road at km 8+240 while Alternative-III is positioned at km 10+309. Alternative-IV is located after the 90° bend of the river at km 11+010. Water conductor system is planned at left bank of Chenab River. An underground power house is planned just downstream of Alternative-III dam axis. The layout of the surge shaft, pressure shaft and pressure tunnel, the powerhouse



including transformer cavern and tailrace tunnels has been kept the same for all three alternatives.

Alternative-I is not considered for the further study as the total storage capacity of Alternative-I is only 5.884 hm3 whereas as per IWT the required live storage is evaluated as about 15 hm3.

Based on the techno-economical evaluation it was found that Alternative-III is the most attractive solution. Alternative-III is further optimized for the dam height varying in between FRL from 2105.0 m asl to 2114.0 m asl keeping the gross head same (99.0 m). It is concluded that most attractive solution is the dam at Alternative-III axis with increase in height by 9.0 m i.e. FRL as 2114.0 m asl. DHPL requested Directorate of Energy - Government of Himachal Pradesh for the change of concession limits of Dugar HEP from FRL as 2105.0 m asl and normal TWL as 2006.0 m asl to FRL as 2114.0 m asl and normal TWL as 2015.0 m asl keeping the gross head same as 99.0 m and without affecting the upstream and downstream projects. Directorate of Energy - Government of Himachal Pradesh has given the approval for the above stated changes in the concession limits of Dugar HEP vide their Letter No. HPDOE/CE (Energy)/Dugar HEP/2014-3596-3600 dated 30th July 2014.

Based on the revised concession limits the capacity of Dugar HEP is estimated as 449 MW. The main components of the project are:

• A 128 m high concrete gravity dam (from the deepest foundation level) located on River Chenab at Latitude N 33° 07’ 05” and longitude E 76° 21’ 20.7”.

• Two numbers main intakes and one intake for auxiliary power house located at the left bank.

• Two numbers main pressure shafts and one pressure shaft for auxiliary power house.

• Underground cavern housing four number main units of 95 MW each and three units of 23 MW each to harness the ecological release.

• Transformer Cavern located upstream of power house cavern.

• Four number main TRTs having Surge Chamber at the upstream end and one TRT for auxiliary power house discharging downstream of dam.

• To facilitate the construction and operation of the project components, suitable adits and access roads have been proposed.

1.9 INTER STATE, INTERNATIONAL OR DEFENCE ASPECT

Since the project is located on Chenab River, this shall be governed by the relevant provisions of the Indus Water Treaty (IWT) which is an International Treaty signed between Government of India and Pakistan in 1960.

CHAPTER 2: SALIENT FEATURES

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Salient Features Dugar Hydro Electric Project 2.1


TABLE OF CONTENT

2 SALIENT FEATURES .................................................................... 2.2

2.1 PROJECT LOCATION ............................................................................................................ 2.2

2.2 HYDROLOGY........................................................................................................................... 2.2

2.3 RESERVOIR .............................................................................................................................. 2.2

2.4 DAM AND SPILLWAYS ........................................................................................................ 2.3

2.5 RIVER DIVERSION AND DIVERSION TUNNEL (DT) ................................................... 2.3

2.6 POWER INTAKE (ON LEFT BANK) .................................................................................... 2.4 2.6.1 Power Intakes for main powerhouse ............................................................................. 2.4 2.6.2 Tunnel intake for auxiliary powerhouse ....................................................................... 2.4

2.7 PRESSURE TUNNEL/ PRESSURE SHAFT ........................................................................ 2.4 2.7.1 Main Pressure Tunnels/shafts .......................................................................................... 2.4 2.7.2 Auxiliary Pressure shaft/tunnel ........................................................................................ 2.5

2.8 POWERHOUSE ....................................................................................................................... 2.5 2.8.1 Main powerhouse (4 x 95 MW) ....................................................................................... 2.5 2.8.2 Auxiliary powerhouse (3 x 23 MW) ................................................................................ 2.6

2.9 TRANSFORMER CAVERN ................................................................................................... 2.6

2.10 SURGE CAVERN/DRAFT TUBE GATE OPERATION CHAMBER............................... 2.7

2.11 TAIL RACE TUNNELS (TRT) ................................................................................................ 2.7 2.11.1 Tail Race Tunnels for Main Plant (4 x 95 MW) ........................................................... 2.7 2.11.2 Tail Race Tunnels for Auxiliary plant (3 x 23 MW) .................................................... 2.7

2.12 POWER BENEFITS ................................................................................................................. 2.8 2.12.1 Main Plant (4 x 95 MW) ...................................................................................................... 2.8 2.12.2 Auxiliary Plant (3 x 23 MW) ............................................................................................... 2.8




2 SALIENT FEATURES

2.1 PROJECT LOCATION

State Himachal Pradesh

District Chamba

River Chenab River

Vicinity Luj village

Latitude 33o 07’ 05” N

Longitude 76o 21’ 20.7” E

Nearest Railhead; Udhampur (J&K) 270 km

2.2 HYDROLOGY

Catchment Area km2 7,823 Snow fed Catchment Area km2 4,458 Total annual inflow in 90% dependable year 106 m3 8,161 Average discharge in 90% dependable year m3/s 257.8 Average Annual Rainfall mm 859.5 Flood Discharge for River diversion (~Q25) Non monsoon Flow

m3/s 870

Flood Discharge for River diversion (~Q25) monsoon Flow

m3/s 2,700

Probable Maximum Flood (PMF) m3/s 9,425

2.3 RESERVOIR

Full Reservoir Level (FRL) m asl 2114.00

Minimum Draw Down Level (MDDL) m asl 2102.35

Design Flood Level (corresponding to PMF) m asl 2114.00

Gross Storage at FRL 106 m3 61.58

Gross Storage at MDDL 106 m3 45.01

Live Storage 106 m3 16.57



2.4 DAM AND SPILLWAYS

Type Concrete Gravity

Design Flood (PMF) m3/s 9,425

Maximum Water Level (MWL) m asl 2114.0

Full Reservoir Level (FRL) m asl 2114.0

Average River Bed Level at Dam Axis m asl 2016.0

Bridge Deck Level m asl 2116.0

Dam Top Level m asl 2116.0

Height of Dam (Above deepest foundation level) m 128.0

Length of Dam Crest m 214.8

Lower level spillway

Crest elevation m asl 2062.50

Gate type and Number of Gates --- Radial, 5 (Five)

Size (W X H) m 8.2 x 11.0

Energy Dissipation System --- Flip bucket

Radius of Bucket m 32

Lip Level of Bucket m asl 2049.15

Upper level spillway

Crest elevation m asl 2102.30

Gate type and Number of Gates --- Radial, 2 (Two)

Size (W X H) m 8.2 x 11.7

Energy Dissipation System --- Flip bucket

Radius of Bucket m 22.5

Lip Level of Bucket m asl 2045

2.5 RIVER DIVERSION AND DIVERSION TUNNEL (DT)

No. of Diversion Tunnels --- 2 Location --- Right Bank Diversion flood (non-monsoon) m3/s 870.0 Diversion flood (monsoon) m3/s 2,700.0 Diameter m 10.5 (Circular) Average Length m 615 Inlet and outlet invert Elevations m asl 2022.0, 2016.0



Upstream Cofferdam Elevation m asl 2049.00 Height of upstream Cofferdam m ~29.0 Downstream Cofferdam Elevation m asl 2026.50 Height of downstream Cofferdam m asl ~10.5 DT intake gate type and number in each DT --- Fixed wheel type, 2 Size of diversion tunnel gates (W X H) m 4. 75 x 10.5

2.6 POWER INTAKE (ON LEFT BANK)

2.6.1 Power Intakes for main powerhouse

Number of openings -- 2 Design discharge per intake m3/s 229.58 Intake Gate Type -- Fixed Wheel - Sill elevation m asl 2084.65 - Dimensions (W x H) m 7.0 X 8.1

2.6.2 Tunnel intake for auxiliary powerhouse

Number of openings -- 1 Design discharge m3/s 87.25 Intake Gate Type -- Fixed Wheel - Sill elevation m asl 2094.85 - Dimensions (W x H) m 4.4 x 5.6

2.7 PRESSURE TUNNEL/ PRESSURE SHAFT

2.7.1 Main Pressure Tunnels/shafts

No. of Pressure Tunnels/ Shafts --- 2 Design Discharge m3/s 229.58 Internal Diameter of Concrete Lined Pressure Tunnel/Shaft

m 8.10

Length of Concrete Lined Pressure Tunnel/Shaft m 183.5, 161 Thickness of Concrete Lining mm 500 Internal Diameter of Steel Lined Pressure Tunnel m 6.70 Quality of Steel -- ASTM A- 537 Class -2 Length of Steel Lined Pressure Tunnel (each) m 68, 78.5 No. of Unit Pressure Tunnels --- 4



Internal Diameter of Unit Pressure Tunnel m 4.75 Length of Unit Pressure Tunnel (each) m 28.4

2.7.2 Auxiliary Pressure shaft/tunnel

No. of Pressure Tunnels/ Shafts --- 1 Design Discharge m3/s 87.25 Internal Diameter of Concrete Lined Pressure Tunnel/Shaft

m 5.60

Length of Concrete Lined Pressure Tunnel/Shaft m 134.7 Thickness of Concrete Lining mm 200 Internal Diameter of Steel Lined Pressure Tunnel m 4.10 Quality of Steel -- ASTM A- 537 Class -2 Length of Steel Lined Pressure Tunnel m 73.7 No. of Unit Pressure Tunnels --- 3 Internal diameter of Unit Pressure Tunnels m 2.40 Length of Unit Pressure Tunnel (each) m 20

2.8 POWERHOUSE

2.8.1 Main powerhouse (4 x 95 MW)

Type Underground Size (L X W X H) including auxiliary powerhouse m 163 x 22.5 x 44.5 Gross Head m 99.0 Length of Main Access Tunnel (7m ‘D’ Shaped) m 665 Turbine type -- Francis Number of units -- 4 Turbine setting elevation m asl 2002.50 Design discharge per unit m3/s 114.79 Rated head m 91.21 Installed capacity per Unit MW 95 Main Inlet valve type Butter fly type Number -- 4 Diameter m 4.0 Generator type 3 Phase Number --- 4 Nominal speed rpm 166.67 Voltage / Frequency kV / Hz 13.8/50 Power factor cos φ 0.9



Normal Tail Water Level m asl 2015.00 Minimum Tail Water Level m asl 2012.26 Probable maximum Tail Water Level m asl 2031.500

2.8.2 Auxiliary powerhouse (3 x 23 MW)

Type Underground Gross Head m 96.12 Turbine type -- Francis Number of units -- 3 Turbine setting elevation m asl 2006.50 Rated discharge per unit m3/s 29.08 Rated head m 89.57 Installed capacity per Unit MW 23 Main Inlet valve type Butter fly type Number -- 3 Diameter m 2.05 Generator type 3 Phase Number --- 2 Nominal speed rpm 500 Voltage / Frequency kV / Hz 11/50 Power factor cos φ 0.9 Normal Tail Water Level m asl 2017.88 Minimum Tail Water Level m asl 2017.26 Probable Maximum Tail Water Level m asl 2042.20

2.9 TRANSFORMER CAVERN

Type --- Underground Cavern Size (L x W x H) m 155 x 14 x 20.5 Transformers for 100 MW machines --- 1 phase Location --- Indoor Number --- 13 Unit capacity MVA 43 Voltage ratio kV / kV 13.80/400 Transformers for 10.5 MW Auxiliary machine --- 3 phase Location --- Indoor Number --- 1 Unit capacity MVA 25



Voltage ratio kV / kV 11/400

2.10 SURGE CAVERN/DRAFT TUBE GATE OPERATION CHAMBER Type Underground Finished size (L x B x H) m 118 x 22 x 47 Number of compartments 4 Size of each compartment (L x B) m 28 x 22 Operation platform level m asl 2036.00 Bottom of surge chamber m asl 1998.35

2.11 TAIL RACE TUNNELS (TRT)

2.11.1 Tail Race Tunnels for Main Plant (4 x 95 MW)

Number of Main TRT’s 2 Finished diameter of Main TRT’s m 8.1 (Circular) Nominal discharge m3/s 229.58 Length of TRT-1 m 385 Length of TRT-2 m 408 No. of draft tube tunnels 4 Length of each draft tube tunnel m 87.4 Finished diameter of draft tube tunnels m 5.7 (Circular) No. of unit tailrace tunnels m 4 Length of each unit tailrace tunnel m 100.3 Finished diameter of unit tailrace tunnel m 5.7 (Circular) TRT Gates Number 4 Type Vertical Size (W x H) m 4.5 x 5.7 Sill elevation m asl 2012.00

2.11.2 Tail Race Tunnels for Auxiliary plant (3 x 23 MW)

Number 1 Finished diameter m 5.6 (Circular) Nominal discharge m3/s 87.25 Length of TRT m 149.3 No. of draft tube tunnels 2 Length of draft tube tunnel m 19, 24 Finished diameter of draft tube tunnels m 3.5 (Circular)



TRT Gates No. 1 Type Vertical fixed wheel Size (W x H) m 2.75 x 3.5 Sill level m asl 2017.00

2.12 POWER BENEFITS

2.12.1 Main Plant (4 x 95 MW)

Annual Energy (in 90% dependable year) GWh 1348.50 Design Energy (at 95% plant availability) GWh 1315.00

2.12.2 Auxiliary Plant (3 x 23 MW)

Energy with 95% plant availability GWh 302.40

CHAPTER 3: JUSTIFICATION OF PROJECT

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Justification of Project Dugar Hydro Electric Project 3.1


TABLE OF CONTENT

3 JUSTIFICATION OF PROJECT ..................................................... 3.4

3.1 POWER SCENARIO IN INDIA ............................................................................................ 3.4

3.2 POWER SCENARIO IN THE NORTHERN REGION ...................................................... 3.7 3.2.1 Power Supply Position during Past Decade ................................................................ 3.8 3.2.2 Power Supply Position for FY 2011-12 ....................................................................... 3.11 3.2.3 Long Term Forecast for Northern Region ................................................................. 3.12

3.3 POWER SCENARIO IN HIMACHAL PRADESH ........................................................... 3.13 3.3.1 Power Supply Position during Past Decade .............................................................. 3.13 3.3.2 Power Supply Position for FY 2011-12 ....................................................................... 3.15 3.3.3 Long Term Forecast for Himachal Pradesh ............................................................... 3.16

3.4 HYDRO POWER DEVELOPMENT ................................................................................... 3.16 3.4.1 Growth of Hydropower upto 9TH Plan ......................................................................... 3.17 3.4.2 10TH Plan Hydro Development ....................................................................................... 3.17 3.4.3 11TH Plan Hydro Development Programme .............................................................. 3.18 3.4.4 Strategy for Hydro Development for Benefits during 12TH Plan ....................... 3.19

3.5 NECESSITY AND JUSTIFICATION ................................................................................... 3.19

3.6 POWER EVACUATION FOR THE PROJECT ................................................................. 3.22




LIST OF TABLES

Table 3.1: Long Term Region wise Forecast ................................................................................................... 3.6

Table 3.2: Installed Capacity of Northern Region as on 31st December, 2013 in MW ................... 3.7

Table 3.3: Availability/Requirement of Energy & Peak Power in Northern Region during Past Decade (2002-03 to 2011-12) ............................................................................................................................... 3.8

Table 3.4: Growth in Energy Generation in Northern Region during Past Decade (2002-03 to 2011-12) ...................................................................................................................................................................... 3.10

Table 3.5: Growth in Installed Capacity in Northern Region during Past Decade (2002-03 to 2011-12) ...................................................................................................................................................................... 3.10

Table 3.6: Energy and Peak Load Demand for the Northern Region (Period 2016– 2022)................ 3.12

Table 3.7: Installed Capacity of Himachal Pradesh as on 31st December, 2013 in MW ............... 3.13

Table 3.8: Energy and Peak Load Demand for Himachal Pradesh (Period 2016 – 2022) ............ 3.16

Table 3.9: Capacity Addition Planned during 11th Plan for All India in MW..................................... 3.18

Table 3.10: Projected Electricity Demand of All India ............................................................................... 3.19



LIST OF FIGURES

Figure 3.1: Shares in Installed Capacity – December 2013 ....................................................................... 3.4

Figure 3.2: Region Wise Power Supply Position during Year 2013-14 ................................................. 3.5

Figure 3.3: Region Wise Peak Demand Position during Year 2013-14 ................................................ 3.5

Figure 3.4: Region Wise Installed Generation Capacity ............................................................................. 3.7

Figure 3.5: Energy Availability and Requirement of Northern Region during Past Decade (2002-03 to 2011-12) ............................................................................................................................................................. 3.9

Figure 3.6: Peak Availability and Requirement of Northern Region during Past Decade (2002-03 to 2011-12) ................................................................................................................................................................... 3.9

Figure 3.7: Actual Energy Availability and Requirement of Northern Region for FY 2011-12 ............. 3.11

Figure 3.8: Actual Peak Availability and Demand of Northern Region for FY 2011-12 ............... 3.12

Figure 3.9: Energy Availability and Requirement of Himachal Pradesh during Past Decade (2002-03 to 2011-12) .............................................................................................................................................. 3.14

Figure 3.10: Peak Availability and Requirement of Himachal Pradesh during Past Decade (2002-03 to 2011-12) ........................................................................................................................................................... 3.14

Figure 3.11: Actual Energy Availability and Requirement of Himachal Pradesh for FY 2011-12 ............. 3.15

Figure 3.12: Actual Peak Availability and Demand of Himachal Pradesh for FY 2011-12 .................. 3.16

Figure 3.13: Plan-wise Growth and Share of Hydropower ..................................................................... 3.17

Figure 3.14: Planned vs. Actual Commissioned Capacity of All India during 11th Plan................ 3.18

Figure 3.15: Growth of Per Capita Electricity Consumption ................................................................... 3.20

Figure 3.16: Peak Percentage Deficit of States in Northern Region for FY 2011-12 .................... 3.21



3 JUSTIFICATION OF PROJECT

3.1 POWER SCENARIO IN INDIA

As per CEA report the total installed generation capacity in our country, which was only 1,358 MW at the time of Independence, is 233,929.94 MW as on 31st December 2013. The share of hydro with 39,893.40 MW capacities is only 17.1%. Thermal (including gas and diesel) accounts for the maximum share of 68.3% with 159,793.99 MW. Nuclear capacity is about 2.0% with 4,780.00 MW and other renewable sources with a capacity of 29,462.55 MW i.e. 12.6%. This is graphically depicted in Figure 3.1.

68.3

17.1

2.0

12.6

100

0

20

40

60

80

100

0

40

80

120

160

200

240

Thermal Hydro Nuclear RES TotalIn

stal

led

Capa

city

(%)

Inst

alle

d Ca

paci

ty (M

W)

Thou

sand

s

Installed Capacity (MW) Installed Capacity (%)

Figure 3.1: Shares in Installed Capacity – December 2013 (Source: CEA website)

The contribution of private sector in the total installed capacity is 76,095.30 MW (32.5%). Share in state sector is maximum with 90,836.70 MW (38.8%) and the remaining share lies with central sector which is 66,997.94 MW (28.7%).

About 68% of India’s total installed capacity is thermal-based. However expansion of this energy source is encountering difficulties because of the burden it places on the infrastructure for supply (mines) and transportation (railways) of coal.

The region-wise distribution of the total power supply and demand position in the country during 2013-2014 (From April 2013 to December 2013) is depicted in Figure 3.2 and the peak demand during this period is shown in Figure 3.3.



6.3

0.9

7.3

1.4

6.3

4.5

-6

-4

-2

0

2

4

6

8

10

0

100

200

300

400

500

600

700

800

Northern Western Southern Eastern North-Eastern

All India

Ener

gy D

efic

it (

%)

Ener

gy R

equi

rem

ent/

Ava

ilabl

e (M

U)

Thou

sand

s

Energy Requirement (MU) Energy Available (MU) Energy Deficit (%)

Figure 3.2: Region Wise Power Supply Position during Year 2013-14

(Source: CEA website)

6.9

2.5

12.5

2.2

5.4

4.2

-9

-6

-3

0

3

6

9

12

15

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20

40

60

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140

160

Northern Western Southern Eastern North-Eastern

All India

Peak

Def

icit

(%)

Peak

Dem

and/

Met

(M

W)

Thou

sand

s

Peak Demand (MW) Peak Met (MW) Peak Deficit (%)

Figure 3.3: Region Wise Peak Demand Position during Year 2013-14




Most of the regions of the country are suffering from power shortages leading to irregular and unreliable supply. The problem becomes acute during peak hours. Based on the projections made in the 17th Electric Power Survey (2007), the all India peak demand will reach to 298253 MW by the year 2021-22, which means an additional generating capacity of about 64,323 MW needs to be added to ensure “Power on Demand” during the next 10 years. This, in effect, means increasing the present installed capacity by 27.5%. Not only the capacity has to be added but also the present hydro-thermal imbalance of 25:75 has to be corrected and brought to 40:60 to meet the peak load requirements, achieve frequency and voltage stability and provide system operating flexibility under changing seasonal and diurnal load pattern. Presently the share of thermal and hydro in the total installed capacity of India is about 85%. If same share (85%) is adopted and for achieving a 40:60 hydro thermal ratio in an additional installed capacity of about 64,323 MW, required by 2021-22, the total requirement of hydro capacity will be 101,400 MW which means about 61,510 MW additional hydro capacity has to be created in the next 10 years.

Beside the proper hydro-thermal balance, with increasing fossil fuel prices and increasing environmental concerns the policy makers are insisting on increasing the dependence on hydro power and other forms of renewable energy. Hydro power in particular has a vast unexploited potential estimated at over 84000MW and is a cleaner source of electricity in long run.

CEA in their 17th Power Survey has indicated long term (2021-22) projections of power demand in the country as shown in Table 3.1 below which indicates that regional distribution of demand for power would be more or less at the current level.

Table 3.1: Long Term Region wise Forecast (Source: 17th EPS)

Energy Requirement (Gwh) Peak load (MW)

Region 2011-12 2016-17 2021-22 2011-12 2016-17 2021-22

NR 294841 411513 556768 48137 66583 89913

WR 294860 409805 550022 47108 64349 84778

SR 253443 380068 511659 40367 60433 80485

ER 111802 168942 258216 19088 28401 42712

NER 13329 21143 36997 2537 3760 6180 Total

(All India) 968659 1392066 1914508 152746 218209 298253

The demand for power in Northern Region is expected to be about 30% of the total demand of India by 2021-22. This is indicative of the need of special efforts to spur the growth of power demand in Northern Region. Such increased demand for power in the region would create employment opportunities and economic activity, which would be beneficial to the Northern Region.



3.2 POWER SCENARIO IN THE NORTHERN REGION

Presently the installed capacity of the Northern Region is 26.8% of the total installed capacity of the country. The region-wise distribution of total installed generation capacity of 233,929.94 MW is shown in Figure 3.4. This includes allocated shares in joint & central sector utilities. Installed capacity of Northern Region as on 31st December 2013 was 62,670.12 MW, comprising 39,627.75 MW (63.2%) of thermal, 15,692.75 MW (25.1%) of hydro, 1,620.00 MW of nuclear (2.6%) and 5,729.62 MW from renewable energy sources (9.1%). Thermal includes 5,031.26 MW of gas turbine, 12.99 MW of diesel generation units and the remaining 34,583.50 MW is based on coal. Sector wise details of the installed capacity of 62,670.12 MW are given in Table 3.2.

Table 3.2: Installed Capacity of Northern Region as on 31st December, 2013 in MW (Source: CEA website)

Sector Hydro Thermal

Nuclear RES Total Coal Gas Diesel Total

STATE 7052.55 14713.00 2579.20 12.99 17305.19 0.00 1221.81 25579.55

PRIVATE 2148.00 7870.00 108.00 0.00 7978.00 0.00 4507.81 14633.81

CENTRAL 6492.20 12000.50 2344.06 0.00 14344.56 1620.00 0.00 22456.76

TOTAL 15692.75 34583.50 5031.26 12.99 39627.75 1620.00 5729.62 62670.12

26.834.7

24.7

12.6

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100.0

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Northern Western Southern Eastern NorthEastern

Islands All India

Inst

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d Ca

paci

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)

Inst

alle

d Ca

paci

ty (M

W)

Thou

sand

s

Installed Capacity (MW) Installed Capacity (%)

Figure 3.4: Region Wise Installed Generation Capacity (Source: CEA website)



Availability Requirement% ShortageAvailability Requirement% Shortage

2002-03 143029.09 155640.67 8.10 21773 24092 9.632003-04 153712.68 163320.18 5.88 22746 24067 5.492004-05 159261.41 177065.84 10.06 24209 26808 9.692005-06 168979.86 190950.37 11.51 25362 29044 12.682006-07 180538.31 202742.75 10.95 26644 31516 15.462007-08 196813.39 220463.39 10.73 29495 32462 9.142008-09 202693.43 227846.43 11.04 29504 33034 10.692009-10 225334.72 254705.72 11.53 31439 37159 15.392010-11 237986.00 258775.00 8.03 34101 37431 8.902011-12 258382.00 276121.00 6.42 37117 40248 7.78

YearEnergy (MU) Peak Power (MW)

3.2.1 Power Supply Position during Past Decade

The availability and requirement of energy and peak power in Northern Region during the past decade is given in Table 3.3. These statistics are also shown in Figure 3.5 & Figure 3.6. During year 2011-12 the energy requirement of the Northern Region was 758.53 MU/day against the available energy of 709.93 MU/day thus leaving a shortage of 48.60 MU/day (6.85%). The maximum requirement in the Northern Region during 2011-12 is reported as 40,248 MW in August 2011 in place of 37,431 MW observed in September 2010 for the previous year. Maximum availability in the Northern Region for 2011-12 was 37,117 MW in July 2011.

(Source: NRPC Annual Report 2011-12)

Table 3.3: Availability/Requirement of Energy & Peak Power in Northern Region during Past Decade (2002-03 to 2011-12)



8.1

5.9

10.111.5 11.0 10.7 11.0 11.5

8.06.4

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YearAvailability Requirement % Shortage


9.63

5.49

9.69

12.68

15.46

9.1410.69

15.39

8.90

7.78

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YearAvailability Requirement % Shortage

Figure 3.6: Peak Availability and Requirement of Northern Region during Past

Decade (2002-03 to 2011-12) (Source: NRPC Annual Report 2011-12)

Figure 3.5: Energy Availability and Requirement of Northern Region during Past Decade (2002-03 to 2011-12)



Growth in energy generation and installed capacity in Northern Region during the past decade as per the Annual Report 2011-12 of Northern Regional Power Committee (NRPC) is given in Table 3.4 & Table 3.5 respectively.

Table 3.4: Growth in Energy Generation in Northern Region during Past Decade (2002-03 to 2011-12)


Year Thermal Hydro Gas Nuclear Total Energy Generation*

2002-03 98724.42 30139.99 17261.41 8418.52 154544.34

2003-04 102704.29 37996.94 20251.12 7157.49 168109.84

2004-05 106451.80 39269.60 19890.54 7069.64 172681.60

2005-06 112572.79 42109.98 19949.49 6221.68 180853.94

2006-07 123797.80 45239.51 20051.05 4520.16 194440.00

2007-08 129111.00 50886.65 19692.06 3147.95 202837.00

2008-09 136233.08 53446.29 20235.15 2995.77 216526.80

2009-10 139393.64 50899.32 23089.88 4320.35 222096.14

2010-11 143604.11 55849.77 21521.64 9591.01 231572.22

2011-12 140925.82 65696.01 21524.26 9862.12 279553.82 (All Figures in MU) *Total Energy includes RES

Table 3.5: Growth in Installed Capacity in Northern Region during Past Decade (2002-03 to 2011-12)


Year Thermal Hydro Gas Nuclear Total Installed

Capacity

2002-03 15469.50 8699.10 3213.20 1180.00 28618.09

2003-04 16004.50 10105.10 3213.20 1320.00 30699.09

2004-05 16789.50 10845.40 3213.20 1180.00 32327.83

2005-06 17592.50 11061.88 3213.20 1180.00 33757.16

2006-07 18027.50 13000.38 3323.20 1180.00 36359.44

2007-08 18877.50 12975.15 3543.20 1180.00 37879.11

2008-09 18807.50 13425.15 3531.19 1180.00 38723.20

2009-10 21275.00 13310.75 3563.26 1620.00 42189.33

2010-11 24232.50 13822.75 4134.76 1620.00 46988.55

2011-12 28357.04 15122.75 4421.26 1620.00 53925.50 (All Figures in MW)



3.2.2 Power Supply Position for FY 2011-12

Actual monthly energy requirement/availability in Northern Region for FY 2011-12 is shown in Figure 3.7. Overall deficit in the Northern Region from April 2011 to March 2012 is 6.4%. Broadly the monthly deficit in the Northern Region lies between 2 to 12%.

4.7 4.0 3.9 2.6 5.16.6

11.49.4 9.1

7.2 6.7 5.8

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-15

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-5

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%)

Ener

gy (

MU

)Th

ousa

nds

Energy Available (MU) Energy Requirement (MU) Energy Deficit (%)

Figure 3.7: Actual Energy Availability and Requirement of Northern Region for FY 2011-12 (Source: CEA website)

Actual monthly peak demand/availability in Northern Region for FY 2011-12 is shown in Figure 3.8. Maximum monthly peak demand in the Northern Region for FY 2011-12 is observed in August 2011 as 40,248 MW which accounts for deficit of 8.8%. Broadly the peak deficit in the Northern Region lies between 4 to 11%.



9.8

6.0 6.4 5.98.8 9.0 10.7

8.5 9.9 8.8 9.6

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(M

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Thou

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Peak Met (MW) Peak Demand (MW) Peak Deficit (%)

Figure 3.8: Actual Peak Availability and Demand of Northern Region for FY 2011-12 (Source: CEA website)

3.2.3 Long Term Forecast for Northern Region

On the basis of the addition of capacity during the 11th & 12th Plan period, the CEA has estimated the requirements of energy and peak load of the Northern Region as shown in Table 3.6.

Table 3.6: Energy and Peak Load Demand for the Northern Region (Period 2016– 2022) (Source: 17th EPS)

Period Energy (GWh) Peak Load (MW)

2016 - 17 411513 66583 2021 - 22 556768 89913

From the above table it can be seen that the peak demand in Northern Region over a period of 10 years is likely to be increased by around 123% from 40248 MW in 2011 – 12 to as much as 89913 MW in 2021-22.



3.3 POWER SCENARIO IN HIMACHAL PRADESH

Himachal Pradesh along with the States of Haryana, Jammu & Kashmir, Punjab, Rajasthan, Uttar Pradesh, Uttaranchal, Chandigarh and Delhi is part of the Northern Region. Installed capacity of Himachal Pradesh as on 31st December 2013, including allocated shares in joint & central sector utilities, was 3824.96 MW, comprising 214.03 MW (5.6%) of thermal, 34.08 MW (0.9%) of nuclear, 2950.94 MW (77.1%) of hydro and 625.91 MW (16.4%) from renewable energy sources. Thermal includes 0.13 MW as gas based, 61.88 MW as diesel based and the remaining 152.02 MW is based on coal. Sector wise details of the installed capacity of 3824.96 MW are given below:

Table 3.7: Installed Capacity of Himachal Pradesh as on 31st December, 2013 in MW



Nuclear RES Total Coal Gas Diesel Total

STATE 393.60 0.00 0.00 0.13 0.13 0.00 625.91 1019.64

PRIVATE 1748.00 0.00 0.00 0.00 0.00 0.00 0.00 1748.00

CENTRAL 809.34 152.02 61.88 0.00 213.90 34.08 0.00 1057.32

TOTAL 2950.94 152.02 61.88 0.13 214.03 34.08 625.91 3824.96

In thermal & nuclear, the installed capacity is allocated from central sector. In thermal the allocation to Himachal Pradesh is mainly from Rihand STPS, Unchahar TPS and Dadri NCGPS etc. In nuclear the allocated installed capacity is from Narora APS and Rajasthan APS.

The coal required for thermal projects is not available in Himachal Pradesh. Therefore pit head power stations are not feasible in the state. For load centre stations the distance from pit head to load centre will increase the cost of coal at load centre. In case of imported coal, apart from its much higher cost as compared to domestic coal, the freight charges for the distance from port to load centre (Himachal Pradesh) will increase the cost of coal at load centre tremendously. Thus use of imported coal is not an economically viable solution for Himachal Pradesh. Further for load centre stations, the rail network is also not well developed in Himachal Pradesh, which is required for coal movement from pit head. Thus the development of thermal power is not very much feasible in the state.

3.3.1 Power Supply Position during Past Decade

Availability and requirement of energy and peak for Himachal Pradesh during past decade are shown in Figure 3.9 & Figure 3.10 respectively.



2.1

0.0

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1.1

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-5-4-3-2-1012345

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%)

Ave

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Ene

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(MU

/Day

)

YearAvailability Requirement % Deficit

Figure 3.9: Energy Availability and Requirement of Himachal Pradesh during Past

Decade (2002-03 to 2011-12) (Source: NRPC Annual Report 2011-12)

0.0 0.0

5.84.9

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4.83.9 3.5

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(%)

Peak

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Figure 3.10: Peak Availability and Requirement of Himachal Pradesh during Past Decade (2002-03 to 2011-12)




During year 2011-12 the energy requirement of Himachal Pradesh was 22.36 MU/day against the available energy of 22.21 MU/day thus leaving a shortage of 0.15 MU/day (0.7%). However, the deficit in meeting the peak requirement was about 7.1%. The maximum requirement in the state during 2011-12 is reported as 1397 MW in February 2012, whereas the maximum availability in the state for 2011-12 was 1298 MW in February 2012.

3.3.2 Power Supply Position for FY 2011-12

Actual monthly energy requirement/availability in Himachal Pradesh for FY 2011-12 is shown in Figure 3.11. Maximum monthly deficit in Himachal Pradesh is observed as 4.8% in December 2012.

1.60.1 0.3

0.30.6

1.90.9

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Energy Available (MU) Energy Requirement (MU) Energy Deficit (%)

Figure 3.11: Actual Energy Availability and Requirement of Himachal Pradesh for FY 2011-12


Actual monthly peak demand/availability in Himachal Pradesh for FY 2011-12 is shown in Figure 3.12. Maximum monthly peak demand in Himachal Pradesh for FY 2011-12 is observed in February 2012 as 1397 MW which accounts for deficit of 7.1%. Maximum peak deficit in Himachal Pradesh is observed as 24% during April 2011.



24.0

0.0 0.03.7

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Peak Met (MW) Peak Demand (MW) Peak Deficit (%)

Figure 3.12: Actual Peak Availability and Demand of Himachal Pradesh for FY 2011-12


3.3.3 Long Term Forecast for Himachal Pradesh

On the basis of the addition of capacity during the 11th & 12th Plan period, the CEA has estimated the requirements of energy and peak load of Himachal Pradesh as shown in Table 3.8. Table 3.8: Energy and Peak Load Demand for Himachal Pradesh (Period 2016 – 2022)

(Source: 17th EPS)

Period Energy (GWh) Peak Load (MW)

2016 - 17 13135 2194 2021 - 22 17657 2907

From the above table it can be seen that the peak demand in Himachal Pradesh over a period of 10 years is likely to be increased by around 108% from 1397 MW in 2011 - 12 to as much as 2907 MW in 2021-22.

3.4 HYDRO POWER DEVELOPMENT

Assessment of demand is an important pre-requisite for planning capacity addition. As per Section 3 (4) of the Electricity Act 2003, Central Electricity Authority (CEA) shall frame a National Electricity Plan once in five years and revise the same from time to time in accordance with the National Electricity Policy. Growth of hydro power during these plans is discussed below.



3.4.1 Growth of Hydropower upto 9TH Plan

The plan wise growth of hydro power in the total installed capacity of the country is shown in Figure 3.13. For 11th plan (2007-12) the data shown in figure is upto 28th February 2011, whereas for other plans the installed capacity is at the end of plan. It could be seen from Figure 3.13 that hydro share was above 45% at the end of 3rd

Plan (1961-66) which was reduced to 25% at the end of 9th Plan (1997-02).

3.4.2 10TH Plan Hydro Development

The Working Group of power for the 10th Plan had recommended need based capacity addition of 41,110 MW which included hydro capacity addition of 14,393 MW comprising of 8,742 MW in central sector, 4,481 MW in state sector and 1,170 MW in Private Sector. However, hydro capacity of 7,886 MW comprising of 4,495 MW in Central Sector, 2,691 MW in State Sector and 700 MW in Private Sector could actually be commissioned during the 10th Plan. Thus only 55% of the planned hydro capacity could be achieved. The main reasons for slippages in 10th Plan are delay in supplies / erection by suppliers / contractor, delay in award of works, delay in clearances / investment decisions, law & order problems and such other reasons like delay in environmental clearances, geological surprises, natural calamities, R&R issues, delay in signing of MOU, court cases, etc.

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city

(MW

)Th

ousa

nds

Hydro Capacity (MW) Total Capacity (MW)

(At t

he e

nd o

f Firs

t

Figure 3.13: Plan-wise Growth and Share of Hydropower




3.4.3 11TH Plan Hydro Development Programme

A capacity addition of 78,700 MW comprising of 59,693 MW from thermal projects, 15,627 MW from hydro projects and 3,380 MW from nuclear projects was planned during the 11th Plan period (2007-12) (Refer Figure 3.14). Only about 70% of the total planned capacity is commissioned at the end of 11th Plan.

Table 3.9: Capacity Addition Planned during 11th Plan for All India in MW (Source: CEA website)


Nuclear Wind Total Coal Gas Diesel Total

STATE 3482.0 19985.0 3316.4 0.0 23301.4 0.0 0.0 26783.4

PRIVATE 3491.0 9515.0 2037.0 0.0 11552.0 0.0 0.0 15043.0

CENTRAL 8654.0 23350.0 1490.0 0.0 24840.0 3380.0 0.0 36874.0

TOTAL 15627.0 52850.0 6843.4 0.0 59693.4 3380.0 0.0 78700.4

15.6

27

59.6

934

3.38

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004

5.54

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399

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54.9

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Hydro Thermal Nuclear Total

Inst

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Planned Commissioned

Figure 3.14: Planned vs. Actual Commissioned Capacity of All India during 11th Plan (Source: CEA website)

Out of 15,627 MW of hydro envisaged for commissioning during 11th Plan, 7,488 MW was planned in Northern Region and 1,672 MW in Himachal Pradesh. Only 1,292 MW is commissioned in Himachal Pradesh by private sector out of planned hydro capacity of 1,672 MW.



3.4.4 Strategy for Hydro Development for Benefits during 12TH Plan

As per the studies carried out by CEA to assess the requirement of additional capacity during the 12th Plan (2012-2017), the requirement of installed capacity to meet the all India peak demand and energy requirement at the end of 12th Plan would require a capacity addition of over 98,400 MW in the 5 years period of 2012-17. About 23,500 MW is achieved by the end of 1st year of 12th Plan. In pursuing low carbon growth strategy, efforts are to maximize exploitation of hydro power potential. This is also necessary for energy security of the country.

3.5 NECESSITY AND JUSTIFICATION

India has been facing electricity shortages in spite of appreciable growth in electricity generation. The demand for electrical energy has been growing at a much faster rate and is expected to increase further to match with the projected growth of Indian economy. The report of the 17th Electric Power Survey, published by CEA, unlike earlier EPS Reports has considered National Electricity Policy target for providing power to all by 2012. In the 17th EPS report the various growth rates have been worked out giving higher weightage to the latest power consumption trend to capture the technological changes and energy conservation efforts in all categories of electricity consumption.

The report has projected electrical energy demand of 1392 Tera Watt Hours for 2016-17 and peak electric demand of 218 Giga Watts. The electrical energy demand for 2021-22 has been estimated as 1915 Tera Watt Hours and peak electric demand of 298 Giga Watts. The demand projections have been made assuming that the utilities would be able to make rigorous efforts in containing T&D losses and adopting Demand Side Management Techniques to achieve high load factors.

The demand projections on all India basis for the year 2016-17 and 2021-22 are given below:

Table 3.10: Projected Electricity Demand of All India

(Source: 17th EPS)

Year Electrical Energy Requirement at Power Station Bus Bars

(GWh)

Annual Peak Electric Load at Power Station Bus Bars

(MW)

2016-17 1392066 218209 2021-22 1914508 298253

The peak demand during 2013-14 has been reached to 135561 MW which is likely to increase to 298253 MW during 2021-22 as projected in the 17th EPS report. In the current financial year i.e. 2013-14, the peak demand has reached to 135561 MW



upto December 2013 with a deficit of 4.2% and the energy requirement has reached to 753829 MU with a deficit of 4.5%.

The per capita electricity consumption which was 18.2 kWh during 1950, has increased to 917.2 kWh during the year 2012-13. The growth of per capita electricity consumption form the year 1950 to 2012-13 is presented in Figure 3.15.

18.2

30.9

45.9

73.9

97.9

126.2

171.6

172.4

228.7

329.2

347.5

464.6

559.2

671.9

883.6

917.2

0 200 400 600 800 1000

1950

1956 (End of 1st Plan)

1961 (End of 2nd Plan)

1966 (End of 3rd Plan)

1969 (End of 3 Annual Plans)

1974 (End of 4th Plan)


1980 (End of Annual Plan)



1992 (End of 2 Annual Plans)




2011-12 (End of 11th Plan)

2012-13 (End of 1st Year of 12th Plan)

Per Capita Consumption (kWh)

Plan

/Yea

r

Figure 3.15: Growth of Per Capita Electricity Consumption

(Source: CEA Website)

The deficit in peak power for all the states in Northern Region for FY 2011-12 is shown in Figure 3.16. It is clear for this figure that there is peak deficit of upto 24% the state of Himachal Pradesh and peak deficit of about 8% the Northern Region during FY 2011-12.

From the growth of peak demand and anticipated installed generating capacity on the basis of schemes proposed for benefits under construction/consideration, it is observed that there is a dire need to provide additional capacity to the Northern grid to meet the increasing demand of the grid. Thus new schemes have to be taken up immediately and be implemented to drive timely benefits.



Considering the present and projected energy and peaking power shortages, addition of Dugar HEP in national grid is very much justified.

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Peak

Def

icit

(%)

Chandigarh Delhi HaryanaHimachal Pradesh Jammu & Kashmir PunjabRajasthan Uttar Pradesh UttarakhandNorthern Region

Figure 3.16: Peak Percentage Deficit of States in Northern Region for FY 2011-12 (Source: NRPC Annual Report 2011-12)

As per annual plan 2008-09 of Government of Himachal Pradesh, the total identified hydro potential is 20415.62 MW. Out of this 2251.0 MW is in Chenab basin. All the available hydro potential of Chenab Basin is unexploited so far. In the annual plan 2008-09, 24 projects have been identified for allotment to IPPs, out of 24 project, 14 projects are in Chenab basin. Dugar HEP is of these 14 projects identified by Government of Himachal Pradesh for allotment to IPP.

Dugar HEP also fits well in the development of Chenab basin as the project located between the Sach Khas HEP on the upstream and Kirthai-I HEP on the downstream utilizes the head available in between upstream and downstream project boundaries.

The implementation of the proposed Dugar HEP (421 MW), will contribute to meeting the power and energy demand in the Northern Region which comes under the purview of Northern Eastern Western and North-Eastern (NEWNE) grid and will



displace electricity that would otherwise have to be produced through the construction of fossil fuel based thermal power plants.

3.6 POWER EVACUATION FOR THE PROJECT

As per power system planning of Northern region grid, generation step-up is proposed at 400 kV level and LILO of one circuit of Reoli – Kishtwar 400 kV D/C at Dugar Generating station. Switchyard capacity to be kept for 1500 MW at Dugar power house. Accordingly, 400 D/C outgoing feeders are considered at Dugar pothead yard.

9 nos 400kV GIS bays i.e. 6 nos for units, 1 no bus-coupler and 2 nos for outgoing feeders shall be installed in GIS hall, located above generator step-up transformers in transformer cavern.

HV side of the generator step-up transformers shall be connected to the GIS through gas to oil bushing and GIB limbs, whereas the LV side of the generator step up transformers shall be connected to the generator terminals through a 13.8 kV isolated phase busduct for 95 MW unit and 11 kV segregated busduct for 23 MW unit. GIS shall be connected to the Pothead yard through 400 kV single phase XLPE cables.

CHAPTER 4: BASIN DEVELOPMENT

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Basin Development Dugar Hydro Electric Project 4.1


TABLE OF CONTENT

4 BASIN DEVELOPMENT ............................................................... 4.2

4.1 MAJOR RIVER SYSTEMS ..................................................................................................... 4.2 4.2 ASSESSMENT OF HYDRO POWER POTENTIAL .......................................................... 4.2 4.2.1 First Survey (1953-59) ......................................................................................................... 4.2 4.2.2 Re-assessment Studies (1978-87) ................................................................................... 4.3 4.3 INDUS BASIN .......................................................................................................................... 4.4 4.4 CHENAB BASIN ...................................................................................................................... 4.5 4.5 FITMENT OF DUGAR HEP IN CHENAB BASIN DEVELOPMENT ............................ 4.6

LIST OF TABLES

Table 4.1: Basin-wise Hydroelectric Potential as per First Survey ........................................................... 4.2

Table 4.2: Basin-wise Hydroelectric Potential as per Re-assessment Study ........................................ 4.3

Table 4.3: Hydroelectric Potential of Indus Basin .......................................................................................... 4.4

Table 4.4: Hydro Power Projects on Chenab River ....................................................................................... 4.6

LIST OF FIGURES

Figure 4.1: Region-wise Distribution of Hydro Potential ............................................................................ 4.4

Figure 4.2: Basin-wise Distribution of Hydro Potential ............................................................................... 4.5

Figure 4.3: Major Hydropower Projects in Chenab Basin ........................................................................... 4.7




4 BASIN DEVELOPMENT

4.1 MAJOR RIVER SYSTEMS

India is endowed with a vast hydropower potential. For the purpose of hydro electric potential survey, the country has been classified into six major river systems. These river systems been further divided into 49 basins. The six major river systems/basins are as follows:

Indus Basin

Ganga Basin

Brahmaputra Basin

Central Indian River System

West Flowing River System

East Flowing River System

4.2 ASSESSMENT OF HYDRO POWER POTENTIAL

4.2.1 First Survey (1953-59)

The first systematic and comprehensive study to assess the hydro-electric resources in the country was undertaken during the period 1953-1959 by the Power Wing of the erstwhile Central Water and Power Commission on the basis of prevailing technology of hydro construction and the constraints imposed by topographical and hydrological considerations etc. These studies placed the economical utilizable hydro power potential of the country at 42100 MW at 60% load factor (corresponding to an annual energy generation of 221 billion units). The basin-wise potential was assessed as below:

Table 4.1: Basin-wise Hydroelectric Potential as per First Survey (Source: CEA website)

River Basin

Potential at 60% Load Factor (MW)

Indus 6583 Brahmaputra 13417

Ganga 4817

Central Indian River System 4300

West Flowing Rivers of Southern India 4350

East Flowing Rivers of Southern India 8633

Total 42100



4.2.2 Re-assessment Studies (1978-87)

The re-assessment studies of hydro-electric potential of the country, completed by Central Electricity Authority in 1987, have placed the hydro power potential at 84044 MW at 60% load factor. A total of 845 hydroelectric schemes have been identified in the various basins which will yield 442 billion units of electricity. With seasonal energy, the total energy potential is assessed to be 600 billion units per year. In addition, the reassessment studies have also identified 56 sites for Pumped Storage Schemes (PSS) with total installation of about 94,000 MW. The hydro potential of 84044 MW at 60% load factor when fully developed would result in an installed capacity of over 1,50,000 MW on the basis of probable average load factor.

The estimated potential of 84,044 MW is distributed across six major basins. About 78% of the estimated hydro potential of the country comes from the Himalayan river systems comprising three basins, namely, Indus, Ganga and Brahmaputra out of which 53% is located in Brahmaputra basin and 47% in Indus and Ganga basins. The remaining 22% potential is distributed in three basins, namely, the central Indian rivers, west flowing rivers and east flowing rivers. The basin wise hydroelectric power potential of the country as per reassessment studies is as under:

Table 4.2: Basin-wise Hydroelectric Potential as per Re-assessment Study (Source: CEA website)

River Basin No. of

Schemes Potential at 60%

Load Factor (MW) Probable Installed

Capacity (MW)

Indus 190 19988 33832

Brahmaputra 226 34920 66065

Ganga 142 10715 20711 Central Indian River System

53 2740 4152

West Flowing Rivers of Southern India

94 6149 9430

East Flowing Rivers of Southern India

140 9532 14511

Total 845 84044 148701

Region-wise distribution of this potential is shown in Figure 4.1. The hydro potential of the Northern Region is 30,155 MW at 60% load factor, which is 35.9% of the total assessed hydro potential of the country. In the Northern Region, hydropower is the most suitable source of power since both thermal and nuclear or other fuel-based source of energy involves carriage of raw material over long distances making the cost of development uneconomical. In the Northern Region,



Jammu & Kashmir with hydro potential of 7487 MW at 60% load factor stands second after Himachal Pradesh with estimated hydro potential of 11647 MW.

Western, 5679, 6.8%Southern, 10763, 12.8%

Eastern, 5590, 6.7%

North Eastern, 31857, 37.9% Haryana, 64, 0.1%

Jammu & Kashmir, 7487, 8.9%

Punjab, 922, 1.1%

Himachal Pradesh, 11647, 13.9%

Rajasthan, 291, 0.3%Uttaranchal, 7453,

8.9%Uttar Pradesh, 2291,

2.7%

Northern; 30155; 35.9%

Total Hydroelectric Potential 84044 MW(At 60% Load Factor)

Figure 4.1: Region-wise Distribution of Hydro Potential (Source: CEA website)

4.3 INDUS BASIN

The Indus, which is one of the greatest rivers of the world, rises near Mansarovar in Tibet and flows through India and Pakistan before fall in the Arabian Sea. Its important tributaries flowing in Indian Territory are Shyok, Nubra, Indus, Satluj, Beas, Ravi, Chenab and Jhelum. The total catchment area of Indus River is 1165500 km2 out of which 321289 km2 lies in India.

As per the reassessment study the hydro potential of Indus basin is estimated as 19988 MW at 60% load factor with a total of 190 hydroelectric schemes. Distribution of this hydro potential in the sub-basins of Indus is given in Table 4.3. The basin has some large multipurpose projects like Bhakra Project; Pong Dam (360 MW); and Ranjit Sagar (600 MW) project and a few large size ROR schemes like Dehar (990 MW); Nathpa Jhakri (1500 MW); Salal (690 MW); Dulhasti (390 MW); Baglihar (450 MW) and various other medium and small ROR schemes.

Table 4.3: Hydroelectric Potential of Indus Basin (Source: Ministry of Water Resources website)

River Basin No. of



Capacity (MW)

Indus 47 1205 2377

Jhelum 22 1632 2657

Chenab 37 5932 11318

Ravi 20 1577 2534



River Basin No. of



Capacity (MW)

Beas 34 1981 3372

Sutlej 30 7661 11574

Total 190 19988 33832

Ganga, 10715, 12.7%

Central Indian Rivers, 2740, 3.3%

Brah

map

utra

, 349

20, 4

1.5%

West Flowing Rivers, 6149, 7.3%

East Flowing Rivers, 9532, 11.3%

Indus, 1205, 1.4%Jhelum, 1632, 1.9%

Chenab, 5932, 7.1%

Ravi, 1577, 1.9%Beas, 1981, 2.4%

Sutlej, 7661, 9.1%

Indus; 19988;23.8%

Total Hydroelectric Potential 84044 MW(At 60% Load Factor)

Figure 4.2: Basin-wise Distribution of Hydro Potential (Source: CEA website)

4.4 CHENAB BASIN

Chenab is the sub-basin of Indus River System. The Chenab River, also known as Chandra Bhaga River in its upper reaches, is one of the major rivers in Jammu & Kashmir. It is formed by the confluence of two rivers viz. Chandra and Bhaga at Tandi near Keylong in Lahaul & Spiti district of Himachal Pradesh. After flowing through Pangi valley in Himachal Pradesh, Chenab River enters into the Paddar area of Kishtwar district of Jammu & Kashmir at EL 1980 m a.s.l. Subsequently it is joined by the largest tributary Marusudar at Bhandarkot at EL 1100 m asl and flows further down upto Akhnoor in Indian Territory. Thereafter it enters into Pakistan. The Chenab River traverses about 584 km in Indian Territory from its source to Akhnoor and is joined by various tributaries in its course.

The Chenab River lying within the Indian Territory is generally rocky as almost the entire river flows through the Himalayan ranges. A small part of the river near Akhnoor, where river emerges out of Himalayan Mountains is comparatively plain. The major portion of the basin receives a considerable amount of snowfall and most of the part of upper reaches remains under snow cover throughout the year. The



main river as well as various tributaries are fed from number of glaciers which make these rivers perennial. The catchment receives rainfall during monsoon as well as during winter periods. Major part of the valley experiences cold climate.

Out of 190 schemes in the Indus basin, 37 schemes are identified in the Chenab basin with a hydroelectric potential of 5932 MW at 60% load factor. Major hydropower projects planned on River Chenab are listed in Table 4.4 and their locations are shown in Figure 4.3.

Table 4.4: Hydro Power Projects on Chenab River

S. No. Name of Scheme Installed Capacity (MW) Status

1 Chhatru 108

2 Seli 400

3 Reoli-Dugli 420

4 Purthi 300

5 Sachkhas 267

6 Dugar 449

7 Kirthai-I 390

8 Kirthai-II 930

9 Kiru 600

10 Kwar 520

11 Dulhasti 390 Commissioned

12 Ratle 850

13 Baglihar I & II 450 + 450 450 MW

Commissioned

14 Swalkot 1200

15 Salal 690 Commissioned

4.5 FITMENT OF DUGAR HEP IN CHENAB BASIN DEVELOPMENT Dugar HEP is one of the scheme identified in the Chenab basin as given in Table 4.4. The project is located near Luj village in district Chamba, Himachal Pradesh. The upstream project (Sachkhas HEP) has tail water level as 2149 masl and Kirthai-I HEP is on downstream of Dugar HEP having full reservoir level as 1895 masl. That means the plants running in tandem will not have any negative effect on their performance and there will be no interference with upstream or downstream projects. Dugar HEP fit well in the Chenab basin between these two projects. Inter-basin transfer is not involved in Dugar HEP.



Figure 4.3: Major Hydropower Projects in Chenab Basin

CHAPTER 5: INTERNATIONAL ASPECTS - INDUS WATER TREATY

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) International Aspect – Indus Water Treaty Dugar Hydro Electric Project 5.1


TABLE OF CONTENT

5 INTERNATIONAL ASPECT - INDUS WATER TREATY ............... 5.2

5.1 GENERAL .................................................................................................................................. 5.2

5.2 THE TREATY ............................................................................................................................ 5.3

5.3 PROVISIONS REGARDING WESTERN RIVERS ............................................................. 5.4

5.4 HYDROELECTRIC PROJECTS ON WESTERN RIVERS ................................................. 5.4 5.4.1 Annexure D of IWT ............................................................................................................... 5.5 5.4.1.1 Design Considerations ......................................................................................................................... 5.6 5.4.1.2 Plant Operation Considerations ....................................................................................................... 5.8 5.4.2 Annexure E of IWT ................................................................................................................ 5.8

5.5 COMMUNICATION WITH PAKISTAN .......................................................................... 5.10

5.6 SETTLEMENT OF DIFFERENCES AND DISPUTES ...................................................... 5.11

LIST OF TABLES

Table 5.1: Aggregate Storage Capacity Allotted to India .......................................................................... 5.9

LIST OF FIGURES Figure 5.1: Rivers of Indus Water System ........................................................................................................ 5.2 © The Copyright remains with AF- Consult Switzerland Ltd.



5 INTERNATIONAL ASPECT - INDUS WATER TREATY

5.1 GENERAL

The Indus Basin is one of the largest river basins in Asia with an approximate area of 1million km2. It extends over four countries in South Asia including China in the north-east, India in the east, Afghanistan in the north-west and Pakistan in the west. More than 50% area of the Indus basin lies within Pakistan.

The largest river in the basin is the Indus River with Chenab, Jhelum, Beas, Ravi and Sutlej Rivers as major tributaries. The major component of the annual flow for these rivers is derived from snowmelt, originating in the Hindukush-Himalayan region. All of the Indus Basin Rivers either originate or pass through India before flowing into Pakistan. A riparian dispute erupted soon after the independence of the two countries in 1947, which was settled in a water sharing treaty. This treaty, called the Indus Water Treaty (IWT), was signed in 1960.

Figure 5.1: Rivers of Indus Water System

Dugar HEP lies on Chenab Main River in Chamba district of Himachal Pradesh, India and is governed by “The Indus Water Treaty 1960” between India and Pakistan. The River Chandra and Bhaga combined near Tandi in Himachal Pardesh, India



considered as tributaries of Chenab, thereafter River is known as The Chenab Main. The Jhelum, The Ravi, The Satluj (The Beas combines in Satluj in India) combines the Chenab in Pakistan and is known as Panjnad. Finally, it combines with The Indus in Pakistan. Rivers of Indus Water System are shown in Figure 5.1.

Planning of Hydro Projects in the Chenab basin has to take into consideration the provisions of the Indus Water Treaty, 1960 (IWT) between India and Pakistan. The Treaty limits the total permissible storage in the Chenab basin at 1.7 Maft. Apart from the storages the IWT permits provision of weekly pondage for ROR schemes located upstream of Ramban (located in Jammu & Kashmir) on the Chenab Main.

The relevant details of the Treaty with implication on Dugar HEP are detailed in this chapter.

5.2 THE TREATY

The Treaty comprises of a Preamble and following 12 Articles and 8 Annexures:

Article I Definitions

Article II Provisions Regarding Eastern Rivers

Article III Provisions Regarding Western Rivers

Article IV Provisions Regarding Eastern Rivers and Western Rivers

Article V Financial Provisions

Article VI Exchange of Data

Article VII Future Co-Operation

Article VIII Permanent Indus Commission

Article IX Settlement of Differences and Disputes

Article X Emergency Provisions

Article XI General Provisions

Article XII Final Provisions

Annexure A Exchange of Notes between Government of India and Government of Pakistan

Annexure B Agricultural Use by Pakistan from Certain Tributaries of the Ravi

Annexure C Agricultural Use by India from the Western Rivers

Annexure D Generation of Hydro-Electric Power by India on the Western Rivers



Annexure E Storage of Waters by India on the Western Rivers

Annexure F Neutral Expert

Annexure G Court of Arbitration

Annexure H Transitional Arrangements

5.3 PROVISIONS REGARDING WESTERN RIVERS

As per definitions given under Article I, the Indus Basin Rivers are categorized in two groups viz. Eastern Rivers (Satluj, Ravi and Beas) and Western Rivers (Indus, Jhelum and Chenab). Under the Treaty, the waters of the Eastern Rivers stand allocated to India and those of Western Rivers largely to Pakistan.

Dugar HEP is located on Chenab River which is under Western Rivers as per IWT.

The provisions regarding the utilization of Western Rivers as per the Article III of IWT are given below:

i. Pakistan shall receive for unrestricted use all those waters of the Western Rivers which India is under obligation to let flow under the provisions of Section ii below.

ii. India shall be under the obligation to let flow all the waters of the Western Rivers, and shall not permit any interference with these waters, except for the following uses:

a. Domestic Use

b. Non-Consumptive Use

c. Agricultural Use (As set out in Annexure C of IWT)

d. Generation of Hydroelectric Power (As set out in Annexure D of IWT)

e. Permitted aggregated storage for single or multipurpose reservoirs as per Annexure E.

iii. Except as provided in Annexure D and E of IWT, India shall not store any water of, or construct any storage works on, the Westerns Rivers.

5.4 HYDROELECTRIC PROJECTS ON WESTERN RIVERS

Annexure D of IWT is about the generation of hydroelectric power by India on Western Rivers. As per Paragraph 1 of the Annexure D, use of waters of Westerns Rivers for generation of hydroelectric power by India, subject to provisions of



Annexure D, shall be unrestricted, provided that the design, construction and operation of new hydro-electric plants which are incorporated in a Storage Work (as defined in Annexure E) shall be governed by the relevant provisions of Annexure E.

5.4.1 Annexure D of IWT

Annexure D of IWT comprises of following parts:

Part 1 Definitions

Part 2 Hydroelectric Plants in Operation or Under Construction as on Effective Date

Part 3 New Run-of-River Plants

Part 4 New Plants on Irrigation Channels

Part 5 General

The relevant definitions mentioned in Part – 1 of Annexure D are given below:

a. "Dead Storage" means that portion of the storage which is not used for operational purposes and "Dead Storage Level" means the level corresponding to Dead Storage.

b. "Live Storage" means all storage above Dead Storage.

c. "Pondage" means Live Storage of only sufficient magnitude to meet fluctuations in the discharge of the turbines arising from variations in the daily and the weekly loads of the plant.

d. "Full Pondage Level" means the level corresponding to the maximum Pondage provided in the design in accordance with Paragraph (c) above.

e. "Surcharge Storage" means uncontrollable storage occupying space above the Full Pondage Level.

f. "Operating Pool" means the storage capacity between Dead Storage level and Full Pondage Level.

g. "Run-of-River Plant" means a hydro-electric plant that develops power without Live Storage as an integral part of the plant, except for Pondage and Surcharge Storage.

h. "Regulating Basin" means the basin whose only purpose is to even out fluctuations in the discharge from the turbines arising from variations in the daily and the weekly loads of the plant.



i. "Firm Power" means the hydroelectric power corresponding to the minimum mean discharge at the site of a plant, the minimum mean discharge being calculated as follows:

The average discharge for each 10-day period (1st to 10th, 11th to 20th and 21st to the end of the month) will be worked out for each year for which discharge data, whether observed or estimated, are proposed to be studied for purposes of design. The mean of the yearly values for each 10-day period will then be worked out. The lowest of the mean values thus obtained will be taken as the minimum mean discharge. The studies will be based on data for as long a period as available but may be limited to the latest 5 years in the case of Small Plants (as defined in Paragraph 18 of Annexure D) and to the latest 25 years in the case of other Plants (as defined in Paragraph 8).

j. "Secondary Power" means the power, other than Firm Power, available only during certain periods of the year.

5.4.1.1 Design Considerations

Dugar HEP is a new Run-of-River plant and qualifies the definition of "Run-of-River Plant" as stated above, therefore, Part – 3 of the Annexure D applies for the Dugar HEP. Part – 3 of the Annexure D has 16 Paragraphs from "8" to "23". Design considerations for Run-of-River plants are given in Paragraph 8, but, as stated in Paragraph 18, these design considerations do not apply to a "Small Plant" which is defined as new Run-of-River plant located on a tributary and which conforms to the following criteria:

a. The aggregate designed maximum discharge through the turbines does not exceed 300 cusecs;

b. No storage is involved in connection with the Small Plant, except the Pondage and the storage incidental to the diversion structure ; and

c. The crest of the diversion structure across the Tributary, or the top level of the gates, if any, shall not be higher than 20 feet above the mean bed of the Tributary at the site of the structure.

Since the design discharge of Dugar HEP is 459.15 m3/s (16,215 cusec) and is more than 300 cusec, Dugar HEP does not qualify the criteria of "Small Plant" and hence the design considerations of Paragraph 8 of Annexure D will be applicable to Dugar HEP. As per Paragraph 8 the Run-of-River plant shall conform to the following criteria (Provisions made in Dugar HEP are furnished below):

a. The works themselves shall not be capable of raising artificially the water level in the Operating Pool above the Full Pondage Level specified in the design.



The pondage i.e. live storage of Dugar HEP is 16.57 Million m3, which is provided to meet the fluctuations in the discharge of the turbines arising from variations in the daily load of plant (as per CEA’s Letter No.2 /HP/52/CEA/2013-PAC/163-64 dated 9th January 2014) . The Full Pondage Level of the Dugar HEP is 2114.0 masl and there is no rising of water in the operating pool of Dugar HEP above the Full Pondage Level.

b. The design of the works shall take due account of the requirements of Surcharge Storage and of Secondary Power.

There is no surcharge storage in Dugar HEP. The power other than firm power is considered as secondary power.

c. The maximum Pondage in the Operating Pool shall not exceed twice the Pondage required for Firm Power.

The firm discharge (Minimum discharge value of average of total discharge series) of Dugar HEP has been worked out as 61.72 m3/s. Twice the pondage required for firm power is worked out as 16.57 MCM. Pondage in operating pool does not exceed twice the pondage required for firm power (as per CEA’s Letter No.2 /HP/52/CEA/2013-PAC/163-64 dated 9th January 2014).

d. There shall be no outlets below the Dead Storage Level, unless necessary for sediment control or any other technical purpose; any such outlet shall be of the minimum size, and located at the highest level, consistent with sound and economical design and with satisfactory operation of the works.

No outlets are foreseen below the dead storage level.

e. If the conditions at the site of a Plant make a gated spillway necessary, the bottom level of the gates in normal closed position shall be located at the highest level consistent with sound and economical design and satisfactory construction and operation of the works.

In Dugar HEP spillway gates arrangement has been provided accordingly.

f. The intakes for the turbines shall be located at the highest level consistent with satisfactory and economical construction and operation of the Plant as a Run-of-River Plant and with customary and accepted practice of design for the designated range of the Plant's operation.

The invert level of main intake is 2085.75 m asl and that of intake for auxiliary unit is 2095.30 m asl. The invert elevation of intake is fixed based on the minimum required submergence criteria from minimum drawdown level of 2102.35 m asl.



5.4.1.2 Plant Operation Considerations

The operation of the works connected with the plant is subject to provisions given in Paragraph 15. Following conditions are applicable to Dugar HEP:

a. The volume of water received in the river upstream of the Plant, during any period of seven consecutive days, shall be delivered into the river below the Plant during the same seven-day period, and

b. In any one period of 24 hours within that seven-day period, the volume delivered into the river below the Plant shall be not less than 30%, and not more than 130%, of the volume received in the river above the Plant during the same 24-hour period.

Provided that:

i. where a Plant is located at a site on the Chenab Main below Ramban, the volume of water received in the river upstream of the Plant in any one period of 24 hours shall be delivered into the river below the Plant within the same period of 24 hours ;

ii. where a Plant is located at a site on the Chenab Main above Ramban, the volume of water delivered into the river below the Plant in any one period of 24 hours shall not be less than 50% and not more than 130%, of the volume received above the Plant during the same 24-hour period.

Paragraph 16 states that for the purpose of above conditions, the period of 24 hours shall commence at 8 A.M. daily and the period of 7 consecutive days shall commence at 8 A.M. on every Saturday and the time shall be Indian Standard Time.

While applying the above stated conditions a tolerance of 10% in volume shall be permissible and the Surcharge Storage shall be ignored as stated in the provisions made in Paragraph 17. The Paragraph 17 also states that the above two conditions shall not apply during the period when the Dead Storage at a Plant is being filled in accordance with the provisions of Paragraph 14. The filling of Dead Storage shall be carried out in accordance with the provisions of Paragraph 18 or 19 of Annexure E.

5.4.2 Annexure E of IWT

The provisions for construction and operation of storage for single or multipurpose reservoirs for India on western rivers are given in Annexure E of Treaty. As per paragraph 7 of Annexure E, the aggregate storage capacity allotted to India on western rivers and its tributaries is shown in Table 5.1.



Table 5.1: Aggregate Storage Capacity Allotted to India

S. No. River system

Conservation Storage Flood Storage General

Storage Power Storage

MAF (hm3) MAF (hm3) MAF (hm3)

(1) (2) (3) (4) (5)

(a) The Indus 0.25 (308.37) 0.15 (185.02) Nil (b) The Jhelum

(excluding the Jhelum Main)

0.50 (616.74) 0.25 (308.37) 0.75 (925.11)

(c) The Jhelum Main Nil Nil

As provided in Paragraph 9

(d) The Chenab (excluding the Chenab Main)

0.50 (616.74) 0.60 (740.09) Nil

(e) The Chenab Main Nil 0.60 (740.09) Nil

Provided that

The storage specified in Column (3) above may be used for any purpose whatever, including the generation of electric energy.

The storage specified in Column (4) above may also be put to Non-Consumptive Use (other than flood protection or flood control) or to Domestic Use.

India shall have the option to increase the Power Storage Capacity specified against item (d) of Table 5.1 by making a reduction by an equal amount in the Power Storage Capacity specified against items (b) or (e) of Table 5.1.

Storage Works to provide the Power Storage Capacity on the Chenab Main specified against item (e) above shall not be constructed at a point below Naunut (Latitude 33° 19' N . and Longitude 75° 59' E.).

The Dugar HEP is situated upstream of the Naunut however no power storage capacity has been provided as per the treaty at this project.

Initial filling of reservoir will be done as per paragraphs 18 & 19 of Annexure E, as given below:

Paragraph 18: The annual filling of Conservation Storage and the initial filling below the Dead Storage Level, at any site, shall be carried out at such times and in accordance with such rules as may be agreed upon between the Commissioners. In



case the Commissioners are unable to reach agreement, India may carry out the filling as follows:

a. if the site is on The Indus, between 1st July and 20th August;

b. if the site is on The Jhelum, between 21st June and 20th August; and

c. if the site is on The Chenab, between 21st June and 31st August at such rate as not to reduce, on account of this filling, the flow in the Chenab Main above Merala to less than 55,000 cusecs.

Paragraph 19: The Dead Storage shall not be depleted except in an unforeseen emergency. If so depleted, it will be refilled in accordance with the conditions of its initial filling.

5.5 COMMUNICATION WITH PAKISTAN

As per paragraph 9 of Annexure D, India shall communicate in writing to Pakistan the information of any new Run-of-River Plant atleast six months in advance of the beginning of construction of river works connected with the Plant as per format specified in Appendix II to Annexure D. The information to be sent to Pakistan broadly includes location of the plant, hydrologic data, hydraulic data and the design particulars pertaining to plant.

As specified in the paragraph 10 of Annexure D, Pakistan shall communicate in writing to India about any objections regarding the design of Plant on the ground of the design criteria specified in paragraph 8 (See section 5.4.1.1) within three months of the receipt of the information submitted by India.

If no objection is received by India from Pakistan within the specified period of three months, then Pakistan shall be deemed to have no objection.

If a question arises as to whether or not the design of a Plant conforms to the criteria set out in Paragraph 8, then either Party may proceed to have the question resolved in accordance with the provisions of Article IX which deals with the settlement of differences and disputes as given in Section 5.6.

Paragraphs 12 (a) and (b) deals with the alteration in design before and after the plant comes into operation respectively. As per paragraph 12 (a) if any alteration proposed in the design of a Plant before it comes into operation would result in a material change in the information furnished to Pakistan under the provisions of Paragraph 9, India shall immediately communicate particulars of the change to Pakistan in writing and the provisions of Paragraphs 10 and 11 shall then apply, but the period of three months specified in Paragraph 10 shall be reduced to two months.

If any alteration proposed in the design of a Plant after it comes into operation would result in a material change in the information furnished to Pakistan under the



provisions of Paragraph 9, India shall, at least four months in advance of making the alteration, communicate particulars of the change to Pakistan in writing and the provisions of Paragraphs 10 and 11 shall then apply, but the period of three months specified in Paragraph 10 shall be reduced to two months.

5.6 SETTLEMENT OF DIFFERENCES AND DISPUTES

In case there are differences between the two parties regarding the interpretation or application of the treaty, first the Permanent Indus Commission will make an effort to resolve the differences by agreement. If the Commission does not reach agreement on the differences between two parties then the differences will be dealt by a Neutral Expert in accordance with the provisions of Annexure F of IWT.

Neutral Expert shall be a highly qualified engineer and shall be appointed as per the provisions of paragraph 4 (b) of Annexure F as follows:

(i) jointly by the Government of India and the Government of Pakistan, or

(ii) if no appointment is made in accordance with (i) above within one month after the date of the request, then by such person or body as may have been agreed upon between the two Governments in advance, on an annual basis, or, in the absence of such agreement, by the International Bank for Reconstruction and Development.

If the Neutral Expert informed the Commission that in his opinion, the difference should be treated as dispute, then the dispute will be resolved in the Court of Arbitration. Establishment of Court of Arbitration shall be in accordance with Annexure G of IWT. As per paragraph 4 of Annexure G Court of Arbitration shall consist of seven arbitrators appointed as follows:

1. Two arbitrators will be appointed by each party.

2. Three arbitrators will be appointed from each of the following categories:

(i) Persons qualified by status and reputation to be Chairman of the Court of Arbitration who may, but need not, be engineers or lawyers.

(ii) Highly qualified engineers.

(iii) Persons well versed in international law.

CHAPTER 6: SURVEY & INVESTIGATIONS

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Survey & Investigations Dugar Hydro Electric Project 6.1


TABLE OF CONTENT

6 SURVEY & INVESTIGATIONS ..................................................... 6.3

6.1 TOPOGRAPHICAL SURVEY ................................................................................................. 6.3 6.1.1 Objectives ................................................................................................................................ 6.3 6.1.2 Control Survey by GPS Trilateration ............................................................................... 6.4 6.1.3 Control Survey by Total Station Traverse ..................................................................... 6.6 6.1.4 Levelling .................................................................................................................................... 6.9 6.1.5 Topographical Surveys ..................................................................................................... 6.10

6.2 GEOLOGICAL AND GEOTECHNICAL INVESTIGATIONS ........................................ 6.11 6.2.1 Regional Geological Studies .......................................................................................... 6.11 6.2.2 Surface Geological Mapping .......................................................................................... 6.11 6.2.3 Sub-Surface Investigations ............................................................................................. 6.12 6.2.4 Laboratory and In-Situ Tests .......................................................................................... 6.16 6.2.5 Site Specific Seismic Studies .......................................................................................... 6.17

6.3 ARCHAEOLOGICAL & MINERAL SURVEY .................................................................. 6.17

6.4 COMMUNICATION SURVEY ........................................................................................... 6.17

6.5 CONSTRUCTION MATERIAL SURVEY .......................................................................... 6.18

6.6 HYDRLOGICAL & METEOROLOGICAL INVESTIGATIONS .................................... 6.18




LIST OF TABLES

Table 6.1: Survey Station Established by Survey of India ............................................................................ 6.4

Table 6.2: Control Stations in the Project Area ............................................................................................... 6.8

Table 6.3: Reference SOI Bench Mark ............................................................................................................. 6.10

Table 6.5: Details of Geological Plan and Sections .................................................................................... 6.12

Table 6.6: The Details of Borehole Investigations Completed at Dugar HEP ................................... 6.13

Table 6.7: Details of Exploratory Drifts Excavated at Dugar Project Area. ......................................... 6.14

Table 6.8: Details of Seismic Refraction Traversing (SRT) at Dugar Project Area ........................... 6.15

Table 6.9: Details of Electrical Resistivity Traversing (ERT) at Dugar Project Area ......................... 6.15

Table 6.10: Details of In-situ Rock Mechanics Tests Completed/ Proposed for Dam/Powerhouse Exploratory Drifts ...................................................................................................................................................... 6.16



6 SURVEY & INVESTIGATIONS

6.1 TOPOGRAPHICAL SURVEY




Topographical survey of the project area is carried out with the objectives of preparing grid maps, establishing ground control points, fixing alignments and obtaining the L-sections and X-sections of the river. To prepare the Topographical maps for this area, the survey agency used advanced survey equipments and techniques including Differential Global Positioning System (DGPS). The latter works on satellite based aerial triangulation methods and collects reference information from the local reference stations placed all over the world. This is a fast and most reliable solution till date for various engineering and navigational purposes. This is mostly used for collection of height (z) values at micro level to be extrapolated into regional level analysis with better accuracy. This is a cost and time effective method.

6.1.1 Objectives

Extensive survey was carried out to cover all project components and fulfil the following objectives:

1. Establishing ground control points at selected places

2. Preparing large scale grid maps at different contour intervals of the proposed dam site, reservoir area, along water conductor system and power house area

3. Obtaining X-sections and L-sections of Chenab River in the entire project length

4. Confirming gross head for power generations

5. Transferring drill holes location to the drawing

6. Confirming the location of exploratory drifts and cross cut

7. Preparing geological map of the area



8. Planning of the layout of the infrastructural facilities required for the project

6.1.2 Control Survey by GPS Trilateration

6.1.2.1 Introduction

Trilateration is a method of control survey in which a net work of triangles is used as in Triangulation. However, in trilateration all the three sides of each triangle are measured in the field. This is in contrast to a triangulation system in which all the horizontal angles are measured and sides are computed trigonometrically with one base measured in the system. The angles in a Trilateration system are computed trigonometrically from the lengths of the sides of the triangle. Trilateration is adjusted after computation of the angles and then the coordinates are determined.

Trilateration is a highly accurate and precise method of establishing and expending horizontal control for precision Engineering Projects. Well shaped strongest system of triangles is maintained to achieve desired strength of figure. The geometrical figures normally used in Trilateration are braced quadrilaterals. These figures are adjusted by the “method of least squares”. This adjustment removes all inconsistencies and gives most probable values of the angles.

6.1.2.2 Methodology

DATA- Control survey by GPS Trilateration was carried out based on survey station Silar h.s. established by Survey of India. (Ref Table 6.1)

Table 6.1: Survey Station Established by Survey of India

Station Latitude Longitude Ellipsoidal Height

Geoidal Height

Silarhs 330 06’39.39689”N 760 23’06.57022”E 3473.0099 3489.746

Instruments Used

1. Leica GPS Sensors (SR-299E)-2Nos.

2. Leica GPS Controllers (CR-244)-2Nos.

3. External Chock Ring Antennas (ATS-303)-2Nos.

4. Psychrometers (Wet and Dry Thermometers)-2Nos.

5. Thommen Barometers (2A2.01.1)-2Nos.

6. Laptop Computers-2Nos.



7. Software- SKI, TGO and Auto Desk Land.

Reconnaissance Paper Reconnaissance - “Map Planning” was carried out on the topographical map Sheet and project map General Layout of Dugar HEP by drawing lines between likely Trilateration points and then studying the strength of proposed Trilateration net. Ground Reconnaissance - Area of project was visited for sites selection of planned points of Trilateration. Ground locations were selected keeping in view of the following:-

(a) That there should be no obstruction below 15º cut of angle i.e., 15º above the horizon all around. The Sky must be clear enough to track the satellites for receiving the signals.

(b) That the presence of any reflecting surface like glass window, water body, shining surface, etc. should be avoided near the observation station, as there is a risk of multi-path error being introduced in the collection of data by the receiver.

(c) That there should be no powerful transmitter like radio/television antenna, high-capacity electric line and other electromagnetic field near the station. These would affect the signals.

(d) That the instrument should be in a safe place and away from the traffic and the passers-by.

(e) Making observation in a very deep valley should be avoided as the sky will be visible much above much above the 15º cut-off angle and only few satellites will be available to the antennae.

With the help of SKI software for selecting the suitable window with four or more satellites above 15º cut-off angle with GDOP<8 and whenever possible 5 or more satellites above 20ºcut-off angle with GDOP<5 at both reference and roving receiver.

6.1.2.3 Observations Differential GPS Static” mode method of surveying was used in the field which is a primary technique. This involves more than one receiver simultaneously collecting data from at least 4 satellites during observation sessions that usually last from 30 minutes to 2 hours for determination of vectors, or baselines between the different static receivers on stations. Thus all the vectors forming the planned figures were



observed for sufficient time. Metrological observations were taken at the beginning and closing of the observations at each station.

6.1.2.4 Data Processing Field data from Leica Controllers was downloaded into the Computer through SKI software. The data was processed under automatic mode from reference point to rover points. After processing all the base lines, a summary was available for scrutinizing the result. All the results were in fixed solution. The efforts to get the fixed solution of all baselines were done by eliminating the different satellites which were not located during the observation and which sent “noisy” signals.

6.1.2.5 Computation (i) Height adjustment was performed for each triangle of the figures from the

difference of heights (∆h=height of Reference station-height of Rover station) obtained from the post processing summary of results in WGS84.

(ii) Calculations for height misclosure in each triangle in the network were cried out and discrepancy adjusted proportional to vector distances.

(iii) Conversion of slope distance to arc distance on WGS84 ellipsoid was carried out using edit & View of SKI software.

(iv) Misclosure in the individual triangle of the Trilateration network coordinates in WGS84 was adjusted proportionate to the ellipsoidal distances obtained.

(v) Trilateration network finally adjusted by “Least square” method.

(vi) Adjusted Spherical coordinates in WGS84 were computed by TGO software.

(vii) Computations of Plane Grid coordinates were also calculated with the help of TGO software after applying all necessary corrections for curvature, convergence, ellipsoid or elevation factors and Grid distances were obtained by applying the required scale factor.

(viii) Orthometric heights were determined by connecting the network with available Geoidal height of Survey of India Bench mark.

(ix) Ellipsoidal heights were also determined from the available data summary of results in WGS84.

6.1.3 Control Survey by Total Station Traverse

6.1.3.1 Introduction

TOTAL STATION TRAVERSE-is a method of for providing supplement to control network of Trilateration and to provide closer and more adequate spacing of horizontal control points. Trilateration net provides a frame work for traverse net of



first and second order accuracies .It is neither economical nor feasible to use Trilateration for closer spacing where traverse can be used efficiently to subdivide the basic network and provide fundamental spacing of control. The traverse is preferably connected to Trilateration stations for closer and adjustment of accuracies.

Total Station Traverse was carried out to provide control points for topographical survey of the components of the proposed structures of Dugar HEP.

6.1.3.2 Methodology

Reconnaissance was carried out in the field based on the planning on the map and stations were selected and marked on the ground keeping in view of the inter-visibility of traverse stations and their suitability for Topographical survey works.

Instruments Used

a. Total Station GPT- 7501 of Topcon make with accuracy 1”

b. Retro directive Prismatic reflectors

c. Binoculars

d. Psychorometers (Wet and Dry Thermometers)

e. Thommen Barometers (2A2.01.1)

f. Laptop Computers

g. Software- TGO and Auto-cad Land Development

Data

Traverse is based on the Trilateration station DG-1 with an arbitrary co-ordinates and true azimuth as given below, obtained from processing of DGPS line DG1→DG13.

Station Northing. Easting. MSL Height Bearing DG1→DG13

DG1 50000.000 50000.000 2487.737 3290 54’14”

6.1.3.3 Observations

1. Traverse observations were started from Trilateration station DG1. Angular measurements were taken using GPT-7501 Total Station of 1” least count. Observations were taken on both faces and two sets of traverse angle were measured. Maximum difference of 5” between two sets was kept.



2. Reciprocal vertical angles were also observed with both sets of traverse angle measurement.

3. Slope distances were also measured in both forward and back directions.

4. Height of Instrument, Height of reflector was recorded at the time of observation of horizontal and vertical angles at both the Instrument and reflector stations.

6.1.3.4 Computations

1. Observed slope distances were reduced to horizontal distances after correcting for refractive index and then applying the slope corrections.

2. Plane rectangular projection was adopted with origin at Trilateration point DG1 true north Azimuth.

3. Traverse Computations were carried out for computation of co-ordinates of traverse stations.

(a) Mean traverse angle and horizontal distances were entered.

(b) Bearings were run down and traverse angles were adjusted for difference of closing bearing by applying the corrections uniformly.

(c) Components of for ΔE and ΔN were computed and closing difference in the co-ordinates was adjusted using the law of proportionate.

(d) Heights were also computed following the trigonometric formula Δh=tanVxD. Where V stands for vertical angle and D stands for horizontal distance.

6.1.3.5 Results

Following is the list of control stations established in the project area.

Table 6.2: Control Stations in the Project Area



S. No. STN NO NORTHING EASTING HEIGHT1 DG-1 50000.000 50000.000 2487.7372 DG-2 52493.290 46528.655 2400.7593 DG-3 54408.043 45424.907 2412.9274 DG-4 55390.695 46834.466 2690.7125 DG-5 56294.350 43516.010 2297.2586 DG-9 56581.994 43871.649 2500.2807 DG-10 56595.965 45231.855 2680.1098 DG-11 52179.560 46081.734 2143.3469 DG-12 50948.422 48342.886 2124.19310 DG-13 51297.465 49247.907 2768.084

6.1.4 Levelling

Trigonometric leveling involves observing the vertical and either the horizontal or slope distance between two points. The difference in elevation can then be calculated by using the trigonometric formula.

Leveling was carried out to establish the height control network for Dugar Hydroelectric project for subsequent topographical surveys.

6.1.4.1 Procedure

This levelling work was executed by dividing the total reach in 29 closing loops by following single territory method by using Digital Level of Model No Leica Sprinter 250M (accuracy level ± 1 mm) and bar coded Gauge pole. The permissible closing error for each loop should not exceed ± 24√K mm, where k is the loop distance in km. Total distance from SOI BM at Gondhla to Killar is about 156 Km.

1. Instruments used

The digital level (automatic level) is an optical instrument that provides a height reference. This reference is a horizontal plane through the axis of the telescope, known as the height collimation. Once the height of collimation has been measured the height of other station can be founded by measuring from this plane with staff. The staff reading of back site is added to the bench mark value to obtain the height collimation and then the reading of foresight is subtracted from height of collimation to obtain the height of foresight. Digital levels detect/scan the reading on the bar code printed on staff and calculate the height of foresight automatically. Model No Leica Sprinter 250M accuracy level ± 1 mm has been used along with bar coded Gauge pole in this assignment.



2. Data used :

Survey of India Bench Mark situated in veranda of PWD Rest-House at Gondhla, District Lahul & Spiti, Himachal Pradesh (Ref Table 6.3).

Table 6.3: Reference SOI Bench Mark

Description Level (masl)

PRIMARY PROTECTED BENCH MARK (Type B), GEODETIC & RESEARCH BRANCH, SURVEY OF INDIA, DEHRADUN at Gondhla

3081.23

6.1.4.2 Computations

There are two method of booking and reduction of level namely Rise and Fall Method- Height of Instrument Method (Height of Collimation Method).

Height of Collimation Method is adopted for computations. The following is the computation procedure:

(i) B. S + R. L = H. I (ii) H. I – I .S = R. L (new) (iii) H. I. (old) – F. S = R. L (new) at change point (iv) R. L. (new) + B.S = H. I. (new)

6.1.4.3 Results

After complete calculation and error distribution level of control point DG2 is computed as 2400.759 masl. While transferring bench mark from Gondhla the prefixed pillar (PH3) of Sachkhas HEP (upstream of Dugar HEP) in connected (TBM 82) and the difference is +4.8 cm is observed.

6.1.5 Topographical Surveys

Detailed survey was conducted after the horizontal and vertical controlling of the Traverse Points, in order to obtain the highest levels of accuracy of the Survey.

Collection of details of manmade and natural features of the area with help of Total station radiation methods. The collected data was down loaded in the computer and further processed for digitization and preparation of digital maps on different scale for different proposed structures of the project. The final survey sheets were plotted with Auto plotter.



The longitudinal section of Chenab River was developed from suspension bridge near Phindro village to Sansari Nala and the cross section of river was developed at various spacing up to elevation of 2120.

6.2 GEOLOGICAL AND GEOTECHNICAL INVESTIGATIONS The surface and sub-surface investigations, which includes surface geological mapping, exploratory drilling, drifting and geophysical profiling, carried out at various project locations with pre defined objectives to delineate the foundation level/grades and to assess the geological conditions of foundation and tunnelling media, which helps in formulating the treatment plan and design recommendations. Geological investigations have been planned with following objectives:

− Surface geological mapping of project components as well as the reservoir area to delineate all the geological features exposed at surface.

− Borehole investigations along the river channel, abutments and tunnel/cavern grades to assess the deepest foundation level, foundation condition, and in- situ permeability of rock mass. The recovered core samples have been subjected to laboratory rock mechanics test to arrive at design geotechnical parameters.

− Geophysical Survey to assess sub-surface foundation condition, which further corroborated with borehole data.

− Exploratory drifting on both the abutments, Intake and power house cavern to access sub surface geological conditions and to conduct various in-situ rock mechanics tests.

− Site Specific Seismic studies to derive earthquake parameters and seismic co-efficient

6.2.1 Regional Geological Studies

For understanding of tectonic and litho-stratigraphic disposition in the project area, the regional geology has been compiled from standard literature by Geological Survey of India & Geological Society of India. The maps are attached as Regional Geological Map (Plate.1, Report on Geological Mapping) and Regional Structural and Tectonic Map (Plate.2, Report on Geological Mapping).

The regional geological studies have been detailed in Geological Mapping Report.

6.2.2 Surface Geological Mapping

Detailed geological mapping of the project area has been carried out with an objective to define the various litho-units along with geotechnical characteristics anticipated to be met at major components of the Project.



The different types of rock and overburden material around project components have been classified to prepare a geological map of the area. Geotechnical parameters of rock outcrops have also been recorded to assess the overall characteristics of rock mass. The data have been utilized in geotechnical evaluation of each component.

The lists of geological plan and sections have been provided in Table 6.5 and geological drawings have been enclosed as Annexure 5, Report on Geological Mapping.

Table 6.4: Details of Geological Plan and Sections Structure Scale Reference

Regional Geological Map 1:500 Plate 1

Regional Structural and Tectonic Map 1:1000 Plate 2

Investigation Plan 1:2500 Plate 3

Geological Map of Dam & Power House Complex Area 1:2000 Plate 4

Detailed Geological Map of Reservoir Area (Sheet 1 to 6) 1:5000 Plate 5

Geological Map Of Project and Reservoir Area 1:15000 Plate 6

Geological Map Of Dam Site 1:1000 Plate 8

Geological Section Along Dam Axis (A-A’) 1:2000 Plate 9Geological Section Across The River D/S of Dam Axis (B-B’) 1:2500 Plate 10Geological Section Across The River D/S Of Dam Axis (Section C-C’) 1:2500 Plate 11Geological Section Along Proposed Water Conductor System (S-S’) 1:2000 Plate 12Geological Section Along Longer Axis of Power House Cavern (X-X’) 1:500 Plate 13

Geological Section Across Power House Cavern (N-N’) 1:500 Plate 14

Geological Map Of HRT Intake Portal 1:500 Plate 15

Geological Wall Log of MAT Portal 1:500 Plate 16

Geological Wall Log of CVT And ADIT Portal 1:500 Plate 17

Geological Wall Log Of TRT Portal 1:500 Plate 18

Geological Map of Diversion Tunnel INLET Portal 1:500 Plate 19

Geological Map of Diversion Tunnel OUTLET Portal 1:500 Plate 20

Geological Section Along DT (Section E-E’) 1:2000 Plate 21

Geological Section Across Reservoir (Section G-G’) 1:5000 Plate 22

Geological Section Across Reservoir (Section H-H’) 1:5000 Plate 23

Geological Section Across Reservoir (Section K-K’) 1:5000 Plate 24

6.2.3 Sub-Surface Investigations

The sub-surface geologic investigations have been completed, which includes the borehole investigations, exploratory drifting and geophysical profiling in order to decipher the foundation level; bedrock depth and thickness of the overburden material and underneath rock profiles at dam and other components. All along the



river channel, series of holes have been drilled to assess the foundation grades and rock mass quality along with in situ permeability tests. Further data was augmented by number of seismic profiles and shear wave.

The borehole logs and drift 3D geological logs have been enclosed as Annexure 1-2, Field and Laboratory Investigation Report.

a. Core Drilling

In project area and its various alternatives, series of boreholes have been completed to assess the sub-surface geological and hydrogeological conditions. The borehole details of the completed hole are given in Table 6.6. The borehole investigation plan has been shown as Plate 1, Field and Laboratory Investigation Report. The geological logs and permeability test data have been enclosed as Annexure 1, Field and Laboratory Investigation Report.

Out of total 16 boreholes (approx. 1280m drill length), 13 have been drilled at dam complex. This includes 3 on each of the abutments, both left and right bank, 5 holes at river gorge, 3 holes on tunnel portals (DT inlet, outlet and Intake-HRT), 1 hole at U/s cofferdam. Based on drill holes at river gorge, the deepest foundation has been assessed.

In-situ permeability tests, both in rock and overburden have been conducted in all the boreholes.

Table 6.5: The Details of Borehole Investigations Completed at Dugar HEP

Borehole No

LocationGround

Eleveation (m)Bed Rock Level

(m)Total Depth

(m)

DH-01 Dam Axis, Right Abt. 2129.10 2128.05 70.00DH-03 Dam Axis, Right Abt. 2041.50 2039.64 80.00DH-04 Dam Axis, Right Bank 2023.00 2011.99 90.00DH-05 Dam Axis, River Centre 2023.64 1991.65 65.00DH-06 Dam Axis, River Centre 2017.30 1990.80 80.00DH-07 Dam Axis, Left Abt. 2040.00 2038.00 80.00DH-09 Dam Axis, Left Abt. 2080.00 2090.00 60.00DH-10 Dam Axis, Left Abt. 2101.30 2096.63 70.00DH-11 Flip Bucket 2020.65 1994.65 143.50DH-13 Plunge Pool 2017.00 1994.94 50.00DH-15 U/s Cofferdam 2019.22 1998.22 31.00DH-16 DT-Inlet 2073.10 2072.10 55.00DH-18 DT-Outlet 2060.00 2056.80 45.00DH-19 Intake-HRT 2124.74 2118.74 50.00DH-21 Power House Complex 2234.59 2192.44 260.00

DH-01 (IVA) Alternate Dam Axis 2011.53 1976.63 50.00



b. Exploratory Drifts

The rocks across the project area are well exposed and this provides substantial opportunity to assess the overall geological structure and to assess the location of any weakness zones which will be critical for abutment conditions. Two exploratory drifts on both abutment of dam have been excavated to assess physico-mechanical properties of the rock and rock mass classification, and to delineate stripping limits to define foundation grades, while a 366m long drift to power house cavern (including three cross cuts) is excavated up to 100m length and are under progress.

The 3D Geological logging of excavated drifts have been enclosed as Annexure 2, Field and Laboratory Investigation Report. The details of exploratory drifts excavated so far are given in Table 6.7.

Table 6.6: Details of Exploratory Drifts Excavated at Dugar Project Area.

S No Exploratory Drift Locations

Tota

l Len

gth

(m)

Alignment Deatils

Leng

th (m

)

Status

Straight 31mCross Cuts 6.5m

Straight 28mCross Cuts 17m



Straight 309m

Cross Cuts 57m

2 DL-2 (Left Abut. at El. 2071.28m) 45m Completed

1 DL-1 (Left Abut. at El. 2046.86m) 37.5 Completed

4 DR-2 (Right Abut. at El. 2065.38m) 47m Completed

3 DR-1 (Right Abut. at El. 2045.00m) 45m Completed

Completed

6PHD (Powerhouse Drift at El. 2036.50m)

366mCompleted up to 100m length

Straight 11m5 IN-01 (Intake at El. 2085.00m) 11m

c. Geophysical Survey

In project domain, the bedrock is exposed predominantly and further detailed sub-surface investigations contribute an important amount of factual data, thus restricting the extensive use of geophysical techniques. However, there are few critical issues and concerns, where geophysical data supplement the already acquired sub surface data base from boreholes and drifts, which will further be helpful in developing a geological model.



Geophysical Investigations using Seismic Refraction techniques as well as Electrical Resistivity sounding have been carried out for Dugar HPP. The geophysical survey has been carried out

considering project geological and topographical conditions, specific objectives and data requirement, depth of interest and operational constraints during the performance of the tests.

A series of Seismic Refraction Test (SRT) and Electrical Resistivity Test (ERT) have been carried out for delineation of sub-surface stratification around the proposed dam complex. Geophysical seismic refraction technique was used in conjunction with Electrical Resistivity Survey to delineate sub-surface stratification at the proposed location. The SRT conducted on the right bank of the river along the river axis and at TRT area while ERT performed at right bank of the river only on 7 profiles along and perpendicular to the river axis.

Table 6.7: Details of Seismic Refraction Traversing (SRT) at Dugar Project Area

S No Profile ID Location Length (m)

1 SRT-1, SEC-1 Dam Site, Left Bank 902 SRT-1, SEC-2 Dam Site, Left Bank 903 SRT-2 Dam Site, Left Bank 90

4 SRT-3,SEC-1 Power House NSL 90

5 SRT-3,SEC-2 Power House NSL 906 SRT-4 Power House NSL 907 SRT-5,SEC-1 Tailrace Tunnels 908 SRT-5,SEC-1 Tailrace Tunnels 90

9 SRT-6,SEC-1 Tailrace Tunnels 90

10 SRT-6,SEC-1 Tailrace Tunnels 90

11 SRT-7 Dam site, Right Bank 90

12 SRT-8 Dam site, Right Bank 90

Table 6.8: Details of Electrical Resistivity Traversing (ERT) at Dugar Project Area

S No Profile ID Location Length (m)

1 ERT-1 Dam site, Right Bank 1802 ERT-2 Dam site, Right Bank 1803 ERT-3 Borrow Site 1804 ERT-4 Alt IV Dam Site 2405 ERT-5 Borrow Site 606 ERT-6 Alt IV Dam Site 207 ERT-7 Alt IV Dam Site 60



The geophysical investigations comprising of SRT and ERT technique were carried out using Seistronix RAS-24, 24-channel Engineering Seismograph and Resistivity Meter–Aquameter CRMAUTO C respectively. SRT has been conducted at 8 proposed profiles while ERT has been at 7 profiles In ERT, both sounding and profiling techniques has been used for delineation of vertical and lateral resistivity variations in the sub-surface (Table 6.8 & Table 6.9).

The detail geophysical report has been enclosed as Annexure 3, Field and Laboratory Investigation Report

6.2.4 Laboratory and In-Situ Tests

The drill core samples have been subjected to various tests in laboratory to determine the mineralogical and geotechnical properties necessary to provide design data on foundation conditions of various structures. The drill core samples from various locations has been collected for laboratory tests, such as, physical properties, slake durability index (SDI), Compressive Strength (Uniaxial and Triaxial) Elastic parameters along with Petrographic Analysis have been conducted. The Shear Parameters (C & Φ) and Modulus and Elasticity (E) and Poisson’s Ratio (v) were estimated. The preliminary report has been enclosed as Annexure 6, Field and Laboratory Investigation Report.

The in-situ tests in exploratory drifts on both abutments of dam have been completed however the test at power house cavern will be carried out once drift is excavated to entire stretch. For evaluation of deformability characteristics of rock mass in abutment drifts, Plate Load Test (PLT) has been conducted. To have an average and representative value to define design modulus, a minimum of two set (one horizontal and vertical direction in one set) in each drift has been completed. For determining the shear strength characteristics of rock mass in abutment drift, block shear tests have been conducted at least on minimum of five test blocks in a drift for determining the shear strength parameters for rock to rock and rock to concrete interfaces with each test block sheared at a different but constant normal stresses.

The details of the in-situ rock mechanics tests have been provided in Table 6.10.

Table 6.9: Details of In-situ Rock Mechanics Tests Completed/ Proposed for Dam/Powerhouse Exploratory Drifts

S.

No. Component Location Drift

No Tests Status

1. Dam Left Abutment

DL-02 1. Shear Test (Rock to Rock) 2. Shear Test (Concrete to

Rock) 3. Deformability test (PLT)

Completed Completed Completed

Right Abutment

DR-01 1. Shear Test (Rock to Rock) 2. Shear Test (Concrete to

Completed



Rock) 3. Deformability test (PLT)

Completed Completed

2. Power House Power House Cavern

PHD 1. Shear test (Rock to Rock) 2. Plate load test 3. Hydro-fracture Test

In Progress

One drift each on each abutments (DL-02 & DR-01) have been selected for in-situ tests and results are summarized in Annexure 5, Field and Laboratory Investigation Report

6.2.5 Site Specific Seismic Studies

As per map of India showing Seismic Zones (IS: 1893 (Part-I) 2002), the Dugar hydroelectric project area is located in the Seismic Zone IV considered as seismically active area. The Site Specific Seismic Design studies have been carried out for determination of MCE and DBE condition by IIT Roorkee. The Peak Ground Acceleration (PGA) values for Maximum Considered Earthquake (MCE) and Design Base Earthquake (DBE) conditions are estimated as 0.47g and 0.24g for horizontal and 0.31g and 0.16g respectively for vertical components.

The interim report on site specific seismic studies has been enclosed as Annexure 4, Field and Laboratory Investigation Report.

6.3 ARCHAEOLOGICAL & MINERAL SURVEY

There is no site in the project area which is notified by archaeological survey of India. No economic mineral deposits are reported in the catchment area of the Chenab River, especially in the reservoir area of the project.

6.4 COMMUNICATION SURVEY

The approach roads to various components of the project for construction as well as permanent access roads are planned from the existing road which is on the right bank of Chenab River. To approach the left bank three bridges are proposed, one temporary bridge upstream of the dam axis and other temporary bridge downstream of the dam axis. One permanent bridge is proposed to reach the power house on the left bank. The detailed planning of roads and bridges is given in Chapter 17 “Infrastructure Facilities” of this report.

The detailed route survey has been conducted from Jammu to Dugar HEP site as well as from Manali to Dugar site to assess the condition of existing roads and bridges for transferring the materials (including Over Dimensioned Consignments) and machineries etc. to the site. Based on the route survey, required measures will be taken to improve the condition of existing roads & bridges (widening, strengthening etc.) during the pre-construction phase of the project.



6.5 CONSTRUCTION MATERIAL SURVEY

The construction of Dugar hydroelectric project envisages construction of 128 m high concrete gravity dam (from deepest foundation level), cofferdams, two diversion tunnels, two intake, twin pressure tunnel, underground power house complex and two tailrace tunnels with installed capacity of 449 MW.

The construction material survey has been made for construction materials, which includes coarse and fine aggregates and borrow area for impervious material in and around the project area. The total requirement of the construction materials for various project components is tentatively estimated to be 18.0 lac cum. A detailed review for the requirement and availability of construction materials for various project components was made. Accordingly, detailed survey has been conducted to identify potential rock quarries / borrows areas for coarse, fine aggregate and impervious clay (refer quarry and borrow area location plans, Annexure 2). The suitability of aggregates have been assessed by laboratory tests and test result have been enclosed as Annexure 7, Field and Laboratory Investigation Report

6.6 HYDRLOGICAL & METEOROLOGICAL INVESTIGATIONS

The hydrological studies for Dugar HE Project have been carried out based on the hydrological and meteorological data of the sites located in the project area and its vicinity on river Chenab as discussed in Volume-II Hydrology. Site specific data is not available. However, Long term discharge is available at Udaipur G & D site on River Chenab. The site is being maintained by CWC and is near to Dugar dam site. Therefore, observed discharge data at Udaipur G & D site has been considered for studies after checking the consistency of the data shared with Pakistan under IWT. Therefore, the discharge data of Udaipur G & D site for the period from 1974-75 to 2011-12 (38 years) has been transposed to Dugar Dam site in catchment area proportion. In addition to the above, a suitable G&D site has been established at about 800 m upstream of project site near Sukrali bridge on River Chenab. The G&D site is being established along with automatic weather station (near Luj village) to collect hydrological and meteorological data. The G&D site is under operation from mid-May 2013 and the automatic weather station is under operation from June 2012. Sophisticated arrangement is being made to observe gauge and discharge data with the help of current meter and automatic water level recorder and to collect suspended sediment and water quality data.

CHAPTER 7: HYDROLOGY

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Hydrology Dugar Hydro Electric Project


APPROVAL NOTE (HYDRLOGY)

Dugar Hydro Power Limited (A Joint Venture of Tata Power & S N Power) Hydrology Dugar Hydro Electric Project 7.1


TABLE OF CONTENTS 7 .......................................................................................................................... HYDROLOGY .................................................................................................................. 7.8

7.1 GENERAL ......................................................................................................... 7.8

7.1.1 Project Proposal ..................................................................................................................................... 7.8 7.1.2 Project Catchment ................................................................................................................................ 7.9 7.1.3 The River System ................................................................................................................................. 7.13 7.1.4 Climatological Characteristics ........................................................................................................ 7.13 7.1.5 Permanent Snowline .......................................................................................................................... 7.14 7.1.6 Pre-Feasibility Study ........................................................................................................................... 7.15 7.1.7 Present Study ........................................................................................................................................ 7.15 7.1.8 Hydrological Data ............................................................................................................................... 7.16 7.1.9 Meteorological Data .......................................................................................................................... 7.18 7.1.10 Discharge Measurement Methodology ...................................................................................... 7.19 7.1.11 Flow Regime .......................................................................................................................................... 7.20 7.1.12 Rainfall Pattern ..................................................................................................................................... 7.23 7.1.13 Mean Monthly Temperature ........................................................................................................... 7.27

7.2 DATA VALIDATION AND CONSISTENCY CHECK ...................................... 7.29

7.2.1 Annual Yield Comparison ................................................................................................................. 7.29 7.2.2 Mass curve ............................................................................................................................................. 7.30 7.2.3 Double Mass Curve ............................................................................................................................ 7.32 7.2.4 Statistical tests ...................................................................................................................................... 7.34 7.2.5 Long-Term Averages 10-daily Flow at G&D Sites .................................................................. 7.35 7.2.6 10-Daily Flow of G&D Sites ............................................................................................................. 7.35 7.2.7 Specific yield at G&D sites ............................................................................................................... 7.56 7.2.8 Quality of Data ..................................................................................................................................... 7.57 7.2.9 Snow studies ......................................................................................................................................... 7.57

7.3 WATER AVAILABILITY ................................................................................. 7.58

7.3.1 Site specific data comparison ......................................................................................................... 7.59 7.3.2 Max., Min., Average, 50% and 90% dependable flow at Dugar diversion site ............. 7.61 7.3.3 Available Flows ..................................................................................................................................... 7.64

7.4 DESIGN FLOOD ............................................................................................. 7.67

7.4.1 General .................................................................................................................................................... 7.67 7.4.2 Design Flood Criteria ......................................................................................................................... 7.67 7.4.3 Present Study ........................................................................................................................................ 7.67 7.4.4 Hydro-Meteorological Approach .................................................................................................. 7.68 7.4.5 Frequency Analysis of Annual Flood Peaks ............................................................................... 7.80 7.4.6 Comparison of Flood by Different Approach ........................................................................... 7.89 7.4.7 Earlier Flood Studies in the Basin .................................................................................................. 7.89



7.4.8 Conclusion ............................................................................................................................................. 7.90

7.5 DESIGN FLOOD FOR RIVER DIVERSION WORKS ...................................... 7.90

7.5.1 Design Flood Criteria ......................................................................................................................... 7.91 7.5.2 Data Available ....................................................................................................................................... 7.91 7.5.3 Statistical Parameters ........................................................................................................................ 7.96 7.5.4 Probability Distribution ..................................................................................................................... 7.96 7.5.5 Conclusion ............................................................................................................................................. 7.98

7.6 SEDIMENTATION STUDY ............................................................................. 7.99

7.6.1 Average annual Sediment Rate ..................................................................................................... 7.99 7.6.2 Original Elevation –Area- Capacity curve .................................................................................7.101 7.6.3 Type of reservoir ................................................................................................................................7.102 7.6.4 Sediment Analysis .............................................................................................................................7.103 7.6.5 Trap Efficiency Computation.........................................................................................................7.104 7.6.6 Estimation of New Zero Elevation ..............................................................................................7.104

7.7 LIMITATIONS OF STUDY ........................................................................... 7.104



LIST OF TABLES Table 7.1: Project Parameters............................................................................................................................... 7.8

Table 7.2: Hypsometric Data at Dugar Diversion Site ............................................................................... 7.11

Table 7.3: Estimation of Zero Degree Isotherms ........................................................................................ 7.15

Table 7.4: Bar Chart showing Availability of Discharge & Rainfall Data ............................................ 7.17

Table 7.5: Catchment Characteristic of various G&D sites...................................................................... 7.18

Table 7.6: Mean Monthly Percentage of Rainfall (Oct 2011 –Dec 2012) at Killar ........................... 7.23

Table 7.7: Mean Monthly Percentage of Rainfall (1951-2001) at Koksar .......................................... 7.24

Table 7.8: Mean Monthly Percentage of Rainfall (1951-2002) at Gondla ......................................... 7.25

Table 7.9: Mean Monthly Percentage of Rainfall at Keylong ................................................................. 7.26

Table 7.10: Mean Monthly Temperature ....................................................................................................... 7.27

Table 7.11: Specific Yield at G&D Sites .......................................................................................................... 7.56

Table 7.12: Daily Observed Discharge Record of Chenab River in at Dugar HEP .......................... 7.61

Table 7.13: 10-Daily flow summary at Dugar HEP ..................................................................................... 7.62

Table 7.14: Detail of 50% and 90% Dependable Flow Year ................................................................... 7.64

Table 7.15: Dependable Flow at Dugar Project and various G&D Sites in Chenab Basin .......... 7.65

Table 7.16: Unit Hydrograph Ordinates ......................................................................................................... 7.72

Table 7.17: Temporal Distribution .................................................................................................................... 7.74

Table 7.18: Design Storm for Dugar HEP ...................................................................................................... 7.75

Table 7.19: 12-hr Bells of 24-hr Design Storm ............................................................................................ 7.76

Table 7.20: Design Flood Ordinates at Dugar Dam Site .......................................................................... 7.77

Table 7.21: Design Flood Ordinates at Dugar Dam Site .......................................................................... 7.78

Table 7.22: Observed Annual Maxima Flood Peaks at Udaipur Site ................................................... 7.80

Table 7.23: Details of Tests ................................................................................................................................. 7.86

Table 7.24: Statistical Parameter ....................................................................................................................... 7.86

Table 7.25: Result of Flood Frequency of Annual Observed Flood Peaks of Udaipur .................. 7.87

Table 7.26: Result of Flood Frequency of Annual Instantaneous Flood Peaks of Udaipur ......... 7.87

Table 7.27: Different Return Period Floods at Dugar Diversion Site ................................................... 7.88

Table 7.28: Comparison of Design Flood by Different Approach at Dugar HEP Site ................... 7.89

Table 7.29: Detail of Non-monsoon (Oct-May) Flood Peaks, Udaipur .............................................. 7.92

Table 7.30: Details of Tests ................................................................................................................................. 7.95

Table 7.31: Statistical Parameter, Non-Monsoon ....................................................................................... 7.96

Table 7.32: Result of Flood Frequency of Non monsoon Flood Peaks of Udaipur ....................... 7.96

Table 7.33: Result of Flood Frequency of Non Monsoon Instantaneous Flood Peaks of Udaipur......................................................................................................................................................................................... 7.97



Table 7.34: Different Return Period Non Monsoon Floods at Dugar Diversion Site .................... 7.97

Table 7.35: Yearly Sediment Rate ...................................................................................................................7.100

Table 7.36: Original Elevation-Area-Capacity at Dugar Diversion Site ............................................7.101



LIST OF FIGURES Figure 7.1: Digital Elevation Model of the Study Area ............................................................................. 7.10

Figure 7.2: Hypsometric Curve-Distribution of Catchment Area at Proposed Diversion Site ... 7.12

Figure 7.3: A View of Chenab River ................................................................................................................. 7.12

Figure 7.4: Automatic Weather Station at Project Site ............................................................................. 7.20

Figure 7.5: Annual Flow regime of Chenab River at Udaipur................................................................. 7.21

Figure 7.6: Non-Monsoon Flow Regime of Chenab River at Udaipur .............................................. 7.21

Figure 7.7: Monthly Flow Distribution at Udaipur ...................................................................................... 7.22

Figure 7.8: 10-Daily average Flow Distribution at Udaipur..................................................................... 7.22

Figure 7.9: Distribution of Mean Monthly Rainfall at Killar ..................................................................... 7.24

Figure 7.10: Distribution of Mean Monthly Rainfall at Koksar .............................................................. 7.25

Figure 7.11: Distribution of Mean Monthly Rainfall at Gondla ............................................................. 7.26

Figure 7.12: Distribution of Mean Monthly Rainfall at Keylong ........................................................... 7.27

Figure 7.13: Mean Monthly Temperature at Killar, Badarwah and Banihal ...................................... 7.28

Figure 7.14: Annual Flow Comparison of Udaipur, Gulabgarh and Benzwar .................................. 7.30

Figure 7.15: Mass Curve of Annual Flow of Chenab River at Udaipur ............................................... 7.31

Figure 7.16: Mass Curve of Annual Flow of Chenab River at Gulabgarh .......................................... 7.31

Figure 7.17: Mass Curve of Annual Flow of Chenab River at Benzwar ............................................... 7.32

Figure 7.18: Double Mass Curve of Annual Flow at Gulabgarh & Udaipur ...................................... 7.33

Figure 7.19: Double mass curve of annual flow at Benzwar and Udaipur ........................................ 7.33

Figure 7.20: Average 10-daily observed flows at Udaipur, Gulabgarh and Benzwar ................... 7.35

Figure 7.21: 10-daily observed flows at Udaipur and Benzwar for 1973-74 .................................... 7.36













Figure 7.34: 10-daily observed flows at Udaipur and Benzwar for 1986-87 ................................. 7.42







Figure 7.39: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1991-92 ............ 7.45


Figure 7.41: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1993-94............. 7.46



Figure 7.44: 10-daily observed flows at Udaipur, Gulabgarh & Benzwar for 1996-97 ............... 7.47







Figure 7.51: 10-daily observed flows at Udaipur and Gulabgarh for 2003-04 ................................ 7.51



Figure 7.54: 10-daily observed flows at Udaipur and Gulabgarh for 2006-07 ............................... 7.52






Figure 7.60: Comparison of derived series with observed data ........................................................... 7.60

Figure 7.61: 10-daily max, min and average computed flow at Dugar HEP .................................... 7.63

Figure 7.62: Flow pattern in 50% and 90% dependable Year at Dugar HEP .................................... 7.63

Figure 7.63: Flow duration curve at Project site (10 daily basis) .......................................................... 7.66

Figure 7.64: Unit Hydrograph for Dugar H E project ................................................................................ 7.73

Figure 7.65: Temporal Distribution Curve of 24-hour Design Storm for Dugar HEP Site ........... 7.75

Figure 7.66: Design Flood (PMF) Hydrograph of Dugar HEP ................................................................. 7.78

Figure 7.67: Design Flood (SPF) Hydrograph of Dugar HEP .................................................................. 7.79

Figure 7.68: Time Series Graph, Udaipur Site .............................................................................................. 7.82

Figure 7.69: Time series graph, Udaipur site ................................................................................................ 7.84



Figure 7.70: Variation of discharge in the river ........................................................................................... 7.90

Figure 7.72: Time series graph, Udaipur site ................................................................................................ 7.93

Figure 7.72: Original Elevation-Area-Capacity curve at Dugar diversion site................................7.101

Figure 7.73: Type of reservoir ..........................................................................................................................7.102



7 HYDROLOGY

7.1 GENERAL The hydrological inputs are very important for the planning, execution and operation of any water resources development project. The hydrological studies are carried out at all the stages of project development starting from the pre-feasibility stage, detailed investigation and are continued even during the operation of the project. Hydrological studies usually carried out for the assessment of quantities of available water at project site and its time variation, estimation of expected flood (usually required for the hydraulic design as well as for safety of the structure) and sedimentation studies, important from life point of view of the project as well as its effect on the live storage.

The catchment of Dugar hydropower project in Chenab basin lies in the state of Himachal Pradesh, a mountainous state in India. The state is situated in Northern India. This state is enriched with several rivers like Satluj, Ravi, Beas and Chenab etc., which originates from mighty Himalayas. They are mostly snow fed and perennial in nature and carry with them floods almost every year during monsoon and have huge hydro potential.

The estimated hydro power potential in Chenab basin is about 22000 MW within Indian Territory. About 34% of this hydro power potential has been identified in Himachal Pradesh alone and balance in Jammu & Kashmir.

7.1.1 Project Proposal

Dugar hydroelectric project is located in Himachal Pradesh on the River Chenab near Killar town as shown in Plate 1. Chenab River is formed after the confluence of two rivers namely Chandra and Bhaga near Tandi. This project envisages an installed capacity of 449 MW (380 MW + 69 MW). The project component comprises of a concrete gravity dam and pressure tunnel with an underground powerhouse on the left bank of Chenab River. Basic project parameters are given in Table 7.1:

Table 7.1: Project Parameters

Nearest Town Killar

District Chamba

Latitude at Dam Site 33º 07’ 10.3” N

Longitude at Dam Site 76º 19’ 35.7” E

River Basin Indus

River/ Tributary Chenab

Catchment Area 7823 km2

Snow fed area 4458 km2



Rain fed area 3365 km2

Installed Capacity 449 MW (380 MW+ 69 MW)

Full Reservoir Level 2114 m asl

MDDL 2102.06 m asl

River Bed Elevation 2015 m (approx)

Gross Storage 53.97 x 106 m3

Live Storage 12.1 x 106 m3

7.1.2 Project Catchment

The project is planned on river Chenab near Killar town. The project basin lies in upper Chenab basin. To assess the catchment area at the proposed dam site, Digital Elevation Model (DEM) data derived from remote sensing data was used for delineation of the catchment and estimation of catchment parameters such as contours river length etc. NASA (National Aeronautics and Space Administration) has provided 90 m (3-arc second) DEM data for nearly 80% of Globe under the program SRTM (Shuttle Radar Topographic Mission): The mission provides near Globe topographic coverage of earth surface with consistency, reliability and accuracy. The DEM data is very useful for hydrological studies where it is difficult to get SOI (Survey of India) topo-sheets of classified area. The DEM data are available in public domain and can be accessed easily. For the catchment area, the 90m SRTM DEM was used for delineating the catchment whose elevation ranges between 2200m in to 6500m. The DEM of the area is shown in Figure 7.1. The DEM was analysed using GIS (Geographical Information System). The sinks were filled in the DEM and flow directions and flow accumulation point were identified before the delineation of main river and their watersheds upto the project site (i.e. project sites whose location and coordinates are known). The stream network for each river catchment was delineated using flow direction method in GIS. In this method, each pixel discharges into one of the eight neighbouring direction having steepest slope. The flow directions are determined by identifying the adjacent neighbouring cell which has the highest positive distance weighted drop. Flow accumulation values of neighbouring surfaces are used for delineating the streams and watersheds. The delineated watershed of Dugar HEP is shown in Plate 2.

Dugar Hydro Power Limited (A Joint Venture of Tata Power & SN Power) Dugar Hydro Electric Project 7.10


Catchment Boundary

Stream

LEGEND

Figure 7.1: Digital Elevation Model of the Study Area



The delineation of stream network and watershed for proposed HEP project reveals the catchment area as under Total catchment area = 7823 Km2 Snow fed area = 4458 Km2 Rainfed area = 3365 Km2 Permanent snowline = 4500 m

The catchment area indicating hydro meteorological stations, snowfed area is at Plate – 2.

The total length of Chenab River up to project diversion site is about 238.25 km in between the diversion site and 4500 m elevation (rain fed area). The slope of the river is about 1 in 115.75. The river bed elevation at dam site is 2015 m. The important streams joining the Chenab River are Miyar Nalla, Chandra, Bhaga, Sansari, Sach Nalla etc.. The distribution of the catchment area against the altitude and hypsometric curve at Dugar diversion site is given in Table 7.2 & Figure 7.2.

Table 7.2: Hypsometric Data at Dugar Diversion Site

S. No. Elevation

(masl)

Catchment below

Elevation (km2)

S. No. Elevation

(masl)

Catchment below

Elevation (km2)

1 2250 23 11 4600 3721

2 2500 100 12 4750 4275

3 2750 203 13 5000 5304

4 3000 400 14 5250 6376

5 3250 681 15 5500 7272

6 3500 1009 16 5750 7699

7 3750 1395 17 6000 7809

8 4000 1916 18 6250 7822.6

9 4250 2570 19 6500 7823

10 4500 3365



2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

0 1000 2000 3000 4000 5000 6000 7000 8000

Elev

atio

n (m

asl)

Area ( Above Elevation, km2)

Figure 7.2: Hypsometric Curve-Distribution of Catchment Area at Proposed Diversion Site

Figure 7.3: A View of Chenab River



7.1.3 The River System

Chenab River is one of the main tributaries of Indus, which drains through Lahaul-Spiti valley of Himachal Pradesh and J&K before joining with Indus in Pakistan. It is formed by confluence of by two streams namely Chandra and Bhaga, which joins West of Keylong at Tandi at El 2820 m. Chandra originates from South of Baralacha Pass and flows through Lahul Valley, whereas Bhaga originates from North of the Baralacha Pass and flows through Spiti valley of Himachal Pradesh in India. During the flow, Chandra changes its course from Northern direction to Western direction, whereas Bhaga directly flows in western direction. Koksar and Keylong are the important places enroute of Chandra and Bhaga respectively. These two streams join at Tandi in Lahaul and form Chandrabhaga or Chenab River which flows through Pangi valley in Himachal Pradesh, Peddar area in J&K towards Indo-Pak Border. During its course of journey various tributaries joins the Chenab, of these, Miyar Nalla from right side at El 2,590 m near Udaipur, Sach Nalla on the right and Luj Nalla near Killar are the main tributaries in Himachal part of Chenab. Sansari Nalla, which joins the Chenab from the right, forms the boundary between HP and J&K. After Sansari Nalla, Chenab enters into Kishtwar area of J&K at El 1,980 m, and is joined by Bhut Nalla at Arthal at El 1785 m. About 55% of the catchment area at the project site remains covered with snow and glaciers and contribute to high flows between March to June due to snow melting. High discharges in the river between July to September are further observed due to monsoon precipitation. During December, January and February when precipitation in the form of rain is negligible and melting of snow is also very low, the discharge in the river is minimum.

7.1.4 Climatological Characteristics

The climate of Chenab basin is affected by the hot tropical weather systems and the cold weather systems known as Western Disturbances. The prime sources of moisture of these disturbances are Mediterranean and the Caspsian seas. The Western disturbances move in the westerly wind regime along Himalayan latitudes during the winter season and have their origins near the Mediterranean Sea. These disturbances may be in the form of a depression or a low-pressure area or an upper air cyclonic circulation or a trough in lower isobaric levels. They shift towards more northern latitudes as the summer season approaches.

This region is a low rainfall area as most of the precipitation in the region is in the form of snow. The rainfall takes place during the monsoon months only and the catchment experiences snowfall during the remaining period of the year. The Southwest monsoon is dominant during July to September, and most of the precipitation is in the form of rainfall. Though total precipitation recorded in this season is only about 29% of the annual precipitation, extreme rainfall floods are also experienced during this season. Severe floods are sometimes recorded during first week of October also. Three raingauge stations namely Keylong, Gondla and



Koksar exist in the catchment. It is observed that the significant runoff in the river results from the melting of snow.

Average maximum temperature at Killar area which is at diversion site ranges from -2.50C in January to 20.20C in July.

Based on available information from different sources the project basin broadly experiences four distinct seasons:

i) The Winter Season : December to March

ii) The Summer/Pre-monsoon : April to June

iii) The Southwest Monsoon : July to September

iv) The Post-monsoon : October to November

7.1.5 Permanent Snowline

“Flood Estimation Report for Western Himalaya, Zone 7, covers Indus river system and Ganga river system. Under the Indus river system river Indus, Jhelam, Chenab, Ravi, Beas and Sutluj has been covered and under the Ganga river system river Ganga Jamuna, Ram Ganga and Sharda have been covered for the purpose of analysis of flood. The permanent snow lines for all these river have been fixed at an elevation of 4500 m. During winter season the snow line dip to height about EL+ 1800M.

Considerable portion of the basin receives precipitation in the form of snow. Estimation of snowline is important to delineate areas contributing snowmelt from the area and the balance area contributing rainfall storm runoff during monsoon.

Mean daily temperature data of Killar and Badarwah (outside the catchment of Dugar HEP) are the two high altitude stations in the basin which have been used to estimate the altitude of zero degree isotherms. These two stations are assumed to represent thermal conditions in the basin. Monthly lapse rates and the corresponding altitude of the zero degree isotherms are given in Table 7.3. The lowest position of the snowline on ground/Stevenson screen level is taken to correspond to the elevation of zero degree isotherms. The altitudes given in Table 7.3 correspond to zero temperature at the height of Stevenson screen.



Table 7.3: Estimation of Zero Degree Isotherms

Baderwah Elevation 1.7 KmKillar Elevation 2.03 km

Month

Lapse rate in Degree C per Km

Altitude of Zero degree iso therm (m)

Altitude of Zero degree iso therm (m)

Killar (Oct 2011-Dec2012) Badarwah (1977-1989)

Killar & Badarwah

based on Killar

based on Baderwah

(Elev. 2.03 km) (Elev. 1.7 km)January -2.5 5.3 23.52 1923.72 1923.72February 0.2 5.6 16.26 2042.30 2042.30March 4.5 9.0 13.57 2361.51 2361.51April 8.7 14.7 18.12 2510.01 2510.01May 4.5 17.9 40.67 2140.66 2140.66June 15.7 22.2 19.57 2832.27 2832.27July 20.2 22.9 8.18 4498.89 4498.89

August 19.4 22.9 10.71 3842.09 3842.09September 16 20.0 12.19 3342.26 3342.26

October 10.4 15.3 14.86 2729.78 2729.78November 7.3 10.8 10.54 2722.90 2722.90December 2.6 6.8 12.76 2233.82 2233.82

Mean Daily Temperature

The above table indicates the altitude of zero degree isotherms as 4498.89 m during the month of July. As such, for the present the permanent snowline has been considered as 4500m. However, an average value of 4500 m above mean sea level has been taken as the permanent snowline for design flood studies of Kirthai I project which is located on the river Chenab.

7.1.6 Pre-Feasibility Study

The Pre- Feasibility study of the Dugar HEP Project has been done earlier by Dugar Hydro Power Limited., which broadly envisaged construction of concrete gravity dam along with intakes on the left bank followed by pressure shafts and an underground power house on the left bank of Chenab River to utilize a gross head of 99 m and to generate 380 MW.

7.1.7 Present Study

The present study aims to carry out hydrological studies based on detailed hydro-meteorological data available in the region so that the proposed project is designed optimally and meets the power requirements.



7.1.8 Hydrological Data

Chenab River and its tributaries are well gauged along its course within state of Himachal Pradesh and Jammu & Kashmir. Meteorological data is being collected by India Meteorological Department (IMD) in the region besides state irrigation department. Most of the gauge discharge measurement sites are maintained by Central Water Commission (CWC). The locations of the G&D station used and the data availability for the study are as under.



Table 7.4: Bar Chart showing Availability of Discharge & Rainfall Data

The discharge data at the G&D sites is at Annexure I to VI. The monthly rainfall data is at Annexure IIA to VA. The monthly temperature data is at Annexure VIA. The monthly silt data is at Annexure VIIA toVIIIA.



7.1.9 Meteorological Data

Precipitation

The precipitation data is being collected at various locations in the Chenab basin. The Dugar HEP is located in the upper reaches of the Chenab basin. Koksar , Keylong and Gondla are the rain gauge stations located within the project basin where long-term rainfall data is available. The period of availability of the rainfall data at Koksar and other stations are given in bar chart in Table 7.4. The monthly rainfall data is at Annexure IIA to VA.

No short term rainfall data is available in or near the catchment.

In addition IMD Pune was requested to supply the list of rain gauge stations whose data is available in the region bounded between latitude 31o 50’ to 33o 36’ and longitude 75o 8’ to 78o22’. IMD Pune vide email dated 13th Dec 2012(Appendix I) informed the availability of 7 rain-gauge stations. However, an examination of IMD data availability reveals that Udaipur rain-gauge station data is available for only two years. As such the same was not procured.

Discharge Data

There exist six G&D sites in Chenab basin where long term discharges are available. However two G&D stations namely Gulabgarh and Benzwar are located downstream of proposed HEP site. The details are given in Table 7.4 and Table 7.5. The 10 daily discharge data as available are at Annexure I to VI. No short term gauge or discharge data is available in the catchment or in the region.

Table 7.5: Catchment Characteristic of various G&D sites

Gauge and Discharge

Site

Total Catchment Area (Km2)

Snow fed area

(Km2)

Rain fed Area (Km2)

% Snow fed area of total

area

% Rain fed area of total

area

Tandi 1653 1125 528 68.00 % 32.00 %

Ghousal 2465 1675 790 67.90 % 32.10 %

Miyar 955 610 345 63.87 % 36.13 %

Udaipur 5910 3758 2152 63.58 % 36.42 %

Dugar 7823 4458 3365 56.97 % 43.01 %

Gulabgarh 8526 4565 3961 53.54 % 46.46 %

Benzwar 10792 5650 5142 52.35 % 47.65 %

Temperature data (Annexure-VIA)

Temperature data for three sites namely Killar, Badarwah and Banihal for varying periods are available in the region. Killar station is located in catchment while



others are outside the catchment. The detail of data availability is indicated in succeeding paras.

Silt Data (Annexure – VIIA and VIII A)

Monthly silt data at Benzwar (1973-74 to 2002-03) and Ghousal (1990-91 to 2011-12) are available in the region.

7.1.10 Discharge Measurement Methodology

Two most commonly methods of discharge measurement in India are by the current meter and by float methods. Though, the discharge measurement by the current meter is more reliable but in hilly regions where the river bed slopes are steep and velocity encountered easily go up to 5-6 meter/sec and due to various constraints faced in lowering the current meter in the river at desired location and depth, the float method is often resorted to.

Discharge measurement at Udaipur site is made by float method once a day. However, multiple gauge readings are taken daily. For measurement of discharge by floats, the flowing portion of river is divided in different segments and up to three floats are thrown in these segments. The surface velocity in each segment is computed by measuring the average time taken by the floats in covering a fixed distance. The surface velocity, thus obtained, is converted in to average velocity for the whole depth by multiplying it with a suitable coefficient. Flow in each segment is calculated by multiplying the cross sectional area of the segment with the average velocity of the segment. Then the segmental discharges are summed up to compute the total discharge in terms of cumec.

DHPL has installed a state of the art Automatic Weather Station along with discharge and silt measurements recently at the Dugar site. The following data is being collected at the site:

(i) Hourly Temperature

(ii) Wind Speed

(iii) Wind Direction

(iv) Sunshine Recorder



Figure 7.4: Automatic Weather Station at Project Site

DHPL is in the process of installing a state of art automatic water level recorder together with cradle and ropeway arrangement for carrying out discharge measurement by current meter. The water level being recorded at short interval will be received automatically at project Head Quarter through VHF link. Silt laboratory will be established for measuring silt concentration and gradation analysis of silt. One ordinary rain gauge (ORG) and one Self Recording Rain Gauge (SRRG) will also be installed at site and will be operational soon from ensuing monsoon season..

7.1.11 Flow Regime

Daily flow data of Chenab River at Udaipur site is available from January 1974 to Sept 2012 i.e. about 38 year. The flow regime of Chenab River can be predicted based on this flow data as under.

A base flow regime is observed from mid October to March. During this period, water originates from soil drainage and limited snowmelt at low altitude during warmer days;

The flow progressively increases from April and May without any rainfall contribution. It is generated by progressive snowmelt and glacier melt. The gradual flow increase during this period corresponds to the increase in daily temperature;



The flow remains high during June to September. The source of inflow is still snow and glacier melt, augmented by monsoon rain on the lower parts of the watershed;

The flow progressively decreases from October to November, except very few isolated event. The sources of water are glacier melt, some post monsoon rain and delayed ground water contribution.

February is the driest month of the year, having only 1.68 % of the total annual flow and minimum water balance carry over.

Figure 7.5: Annual Flow regime of Chenab River at Udaipur

Figure 7.6: Non-Monsoon Flow Regime of Chenab River at Udaipur



Figure 7.7: Monthly Flow Distribution at Udaipur

The two extreme months over the year are July and February. Maximum flow in the stream remains during the July i.e. 24.83 % and minimum flow i.e. 1.68 % in the month of February as shown in Figure 7.7.

The 10- daily flow data is available from 1974-75 to 2011-12 i.e. about 38 years. Average 10 daily flows based on observed 38 years of available data is plotted in Figure 7.8 below. A perusal of the same indicates that the region experiences heavy flows during the period of June to September. Low flows occur during October to March. The flow starts increasing during April to May due to contribution of snowmelt.

Figure 7.8: 10-Daily average Flow Distribution at Udaipur



7.1.12 Rainfall Pattern

In Himalayan region spatial precipitation distribution shows high variations. Research studies have shown that these variations are the result of catabolic and thermal winds which causes localized winds with strong circulation. As a result less precipitation occurs in the lower reaches of the valley in comparison to mountain ridges.

The collection of daily rainfall data of most of the rain gauges are done manually in India. Keeping in view the convenience in collection of daily rainfall record and maintenance and safety of instrument mostly rain gauges in mountains are placed near the population in the valley floor. Very few rain gauges are located on the mountain ridges, where access and daily logging of the rainfall data is difficult. As a result actual estimation of the catchment precipitation is very difficult for the mountainous region.

Koksar, Killar, Gondla and Keylong are the rain gauge stations located within the project basin where monthly rainfall data is available as shown in Table 7.4. Besides these stations, rainfall data of Kishtwar rain gauge stations located outside the catchment in J&K is also available whose details are in Table 7.4. The available rainfall data at rain gauge stations have been analyzed. The average monthly and annual rainfall, highest amount of rainfall and monthly distribution of rainfall received at (available) rain gauge stations are illustrated below in the tables and figure.

Table 7.6: Mean Monthly Percentage of Rainfall (Oct 2011 –Dec 2012) at Killar

S. No. Month Average Monthly Rainfall

(mm) % of Annual

value 1. JAN 35.3 4.11

2. FEB 140.0 16.29

3. MAR 162.8 18.94

4. APR 141.6 16.47

5. MAY 162.8 18.94

6. JUN 19.2 2.23

7. JUL 19.3 2.25

8. AUG 44.6 5.19

9. SEP 82.9 9.65

10. OCT 19.1 2.22

11. NOV 15.5 1.80

12. DEC 16.5 1.91

Total 859.5 100



Figure 7.9: Distribution of Mean Monthly Rainfall at Killar

Following conclusion may be drawn from above analysis:

The highest amount of rainfall is received in the month of March and May.

The minimum rainfall during the month of November.

The average annual rainfall at Killar is 859.5 mm.

Table 7.7: Mean Monthly Percentage of Rainfall (1951-2001) at Koksar


(mm) % of Annual

value 1. JAN 159.2 12.53

2. FEB 167.0 13.14

3. MAR 169.7 13.36

4. APR 97.2 7.65

5. MAY 103.5 8.15

6. JUN 53.4 4.21

7. JUL 134.5 10.59

8. AUG 107.7 8.48

9. SEP 109.5 8.62

10. OCT 66.3 5.22

11. NOV 34.6 2.73

12. DEC 67.6 5.32

Total 1270.2 100



12.5313.14 13.36

7.658.15

4.21

10.59

8.48 8.62

5.22

2.73

5.32

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Mon

thly

Rai

nfal

l %

Monthly Rainfall distribution at Koksar in percentage

Figure 7.10: Distribution of Mean Monthly Rainfall at Koksar


The highest amount of rainfall is received in the month of March and February.

The minimum rainfall during the month of November.

The average annual rainfall at Koksar is 1270.2 mm

Table 7.8: Mean Monthly Percentage of Rainfall (1951-2002) at Gondla


(mm) % of Annual value

1. JAN 116.8 12.72

2. FEB 110.3 12.01

3. MAR 146.9 16.00

4. APR 111.7 12.16

5. MAY 90.0 9.80

6. JUN 28.4 3.09

7. JUL 64.7 7.04

8. AUG 49.1 5.35

9. SEP 61.4 6.69

10. OCT 48.6 5.30

11. NOV 32.2 3.51

12. DEC 58.2 6.34

Total 918.3 100



12.7212.01

16.00

12.16

9.80

3.09

7.04

5.35

6.69

5.30

3.51

6.34

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Mon

thly

Rai

nfal

l %

Monthly Rainfall distribution at Gondla in percentage

Figure 7.11: Distribution of Mean Monthly Rainfall at Gondla


The highest amount of rainfall is received in the month of March.

The average annual rainfall at Gondla is 918.3 mm

Table 7.9: Mean Monthly Percentage of Rainfall at Keylong


(mm) % of Annual value

1. JAN 67.3 8.66

2. FEB 56.1 7.22

3. MAR 139.6 17.97

4. APR 91.3 11.76

5. MAY 80.5 10.37

6. JUN 37.6 4.84

7. JUL 76.3 9.82

8. AUG 45.3 5.83

9. SEP 81.5 10.49

10. OCT 39.4 5.07

11. NOV 19.5 2.51

12. DEC 42.3 5.45

Total 776.6 100



Figure 7.12: Distribution of Mean Monthly Rainfall at Keylong


The highest amount of rainfall is received in the month of March.

The average annual rainfall at Keylong is 776.6 mm

An examinations of rainfall data of the three rain-gauge stations located in-side the catchment reveals similar trend i.e maximum precipitation occurs during the month of March ( non-monsoon period) and minimum during the month of November.

7.1.13 Mean Monthly Temperature

The temperature records (long term) are available at Killar, Badarwah and Banihal stations located in the Chenab river basin. The minimum mean monthly temperature is recorded in the month of January. The hottest month in the basin is July. Killar station is located in the catchment while the others are located outside the catchment.

Table 7.10: Mean Monthly Temperature

Month Mean Monthly Temperature ( oC )

Killar (Oct 2011-Dec 2012)

Badarwah (1977-1989)

Banihal ( 1962-2002)

Jan -2.5 5.3 4.9

Feb 0.2 5.6 6.1



Month Mean Monthly Temperature ( oC )

Killar (Oct 2011-Dec 2012)

Badarwah (1977-1989)

Banihal ( 1962-2002)

Mar 4.5 9.0 10.1

Apr 8.7 14.7 15.0

May 4.5 17.9 18.2

June 15.7 22.2 21.8

July 20.2 22.9 23.0

Aug 19.4 22.9 22.5

Sept 16.0 20.0 19.7

Oct 10.4 15.3 15.4

Nov 7.3 10.8 11.0

Dec 2.6 6.8 7.2

Figure 7.13: Mean Monthly Temperature at Killar, Badarwah and Banihal

The above table and plot reveals that Killar experiences extremely low temperature during the month of January. The maximum temperature is recorded during the month of July at all locations. Winter season is during the period of November to March except at Killar where low temperature was noticed during the month of May also.



7.2 DATA VALIDATION AND CONSISTENCY CHECK The inconsistency in the data may be either due to human or instrumental error. If inconsistencies are identified in the observed data, then it may be removed and data may be adjusted with the help of some well established hydrological techniques. The rainfall data is available at three rain-gauge stations which are located unevenly in the catchment. Their locations are such that it is difficult to carry out isohyetal or Theissen polygon analysis for assessment of catchment rainfall. The rain gauge stations namely Koksar, Gondla and Keylong are located nearby while no station is located in upper and lower reaches of the catchment. The rainfall data availability is not concurrent even for these three rain-gauge stations with the observed discharges. As such runoff data validation with rainfall was not carried out. The observed flow data of river Chenab where long term discharge data are available namely Udaipur, Gulabgarh and Benzwar shall be utilized for the present study and accordingly the same have been examined for their consistency by some of the hydrological practices/techniques as given below:

• Annual Yield Comparison of G&D sites

• Mass curve

• Double Mass curve

• Statistical Tests

• Long-term averages 10-daily flow at G&D sites

• 10-daily flow of G&D sites

• Specific yield at G&D sites

7.2.1 Annual Yield Comparison

The annual volumes of the nearby G&D sites are plotted on the same graph for checking the consistency/trend in the pattern of annual flow volumes. The Udaipur G&D site of CWC is located on river Chenab in the upstream of Dugar diversion site while Gulabgarh and Benzwar sites of CWC are located downstream of Dugar diversion site. The annual flow volumes of Udaipur, Gulabgarh and Benzwar sites in MCM are plotted on the same plot for the comparison.



Figure 7.14: Annual Flow Comparison of Udaipur, Gulabgarh and Benzwar

Pattern of annual flow volumes of river Chenab at Udaipur are showing consistency and trend with the annual flow volumes of river Chenab at Benzwar but shows inconsistency with Gulabgarh data for the period 2000 to 2004. Both Benzwar and Udaipur shows rising trend from 2002-03 onwards while Gulabgarh indicates falling trend. It appears that the data during this period at this site contains some observational errors.

7.2.2 Mass curve

The consistency of the annual flow volumes of a particular G&D site may also be checked with the help of plotting the mass curve of annual observed flow. The straight line of the mass curve indicates the consistency in the annual flow measurement. The change in the slope of the mass curve generally due to the upstream utilization or change in the method of discharge observation. The mass curve of annual flow volumes at Udaipur, Gulabgarh & Benzwar stations are shown below.



Figure 7.15: Mass Curve of Annual Flow of Chenab River at Udaipur

Figure 7.16: Mass Curve of Annual Flow of Chenab River at Gulabgarh

The above Mass curve for Gulabgarh indicates a kink during the year 2003-04. Discrepancy was noticed in the annual yield comparison in earlier para also. This



correlates the findings made in earlier para. The utilization of Gulabgarh data therefore needs more detailed examination.

Figure 7.17: Mass Curve of Annual Flow of Chenab River at Benzwar

7.2.3 Double Mass Curve

The consistency of the annual flow volumes of one G&D site may also be checked with the annual flow volumes of another G&D site located either on the same river or in the vicinity in hydro-meteorological similar region. In the present case, the annual flow of Udaipur site which is located on the same river have been plotted for same period with Gulabgarh and Benzwar in double mass curve. Double mass curve between Udaipur and Gulabgarh shows kink, where as Udaipur and Benzwar curves are nearly in straight line. It suggests that the data of Udaipur and Benzwar are more consistent as compared to Gulabgarh. Udaipur and Benzwar has very good correlation, but correlation between Udaipur and Gulabgarh is not that good. It shows that data at Gulabgarh is not consistent with respect to other stations. This was noticed in earlier paras. As such Gulabgarh data is not considered for hydrological studied for the proposed HE project. However, the Double mass curve of annual flow between Gulabgarh and Benzwar are indicated in Figure 18 and 19 below.



Figure 7.18: Double Mass Curve of Annual Flow at Gulabgarh & Udaipur

Figure 7.19: Double mass curve of annual flow at Benzwar and Udaipur



7.2.4 Statistical tests

Student T test and F test have been carried out for the observed 10 daily flows of Udaipur G&D site for the period 1974-75 to 2011-12. The flow series have been bifurcated in two equal parts while carrying out the relevant tests. The results indicated below reveals that the test values are within the permissible critical limits.

T test

F test

An examination of above table indicates that T-test corresponding to two tails is less than the critical value. Further since F statistics is 0.8813 ( nearly equal to unity) signifies that both the series are not significantly different and null hypothesis is true. Also the T statistics is less than T-critical thereby indicating better data quality.



7.2.5 Long-Term Averages 10-daily Flow at G&D Sites

Long term averages of 10-daily flows observed at G&D sites are plotted on the same plot to indicate an idea of variability of the stream flow with in the year time. Long term averages of 10-daily flow observed at Udaipur, Gulabgarh and Benzwar G&D sites are plotted on the same plot.

The flow in the river is maximum in the month of July. Lowest flows are recorded in the month of January, February and March. The river flow start rising by the end of March when probably contribution from snow melting start. The three discharge observation sites exhibit similar 10 daily trend. However variations were noticed during year to year basis in succeeding paras.

Figure 7.20: Average 10-daily observed flows at Udaipur, Gulabgarh and Benzwar

7.2.6 10-Daily Flow of G&D Sites

The validation and the consistency checks carried out on the annual flow series at the Udaipur site in the earlier paras have shown that the annual flow series at Udaipur is consistent. The 10-daily flow of all the G&D sites is plotted on the same graph during each year to check the consistency of the flow in each 10-daily period. The 10-daily flow observed at Benzwar, Gulabgarh and Udaipur G&D sites are plotted year wise on the same figure as under.



Figure 7.21: 10-daily observed flows at Udaipur and Benzwar for 1973-74




































Figure 7.39: 10-daily observed flows at Udaipur, Gulabgarh and Benzwar for 1991-92









Figure 7.44: 10-daily observed flows at Udaipur, Gulabgarh & Benzwar for 1996-97















Figure 7.51: 10-daily observed flows at Udaipur and Gulabgarh for 2003-04

















An examination of the above plots on 10 daily basis (yearly basis) at the three G&D sites viz. Udaipur (CA = 5910 Sq.km), Gulabgarh (CA = 8526 Sq.km) and Benzwar (CA = 10792 Sq.km) exhibits variable flows as under:-

Gulabgarh though intercepts less area as compared to Benzwar experiences more runoff during the month of July and August for the period 1994-95 till 1998-99.

Similarly, the flows recorded at this site during 1999-2000 till 2004-05 and 2010-11 were either equal or less than the flows recorded at Udaipur.

Gulabgarh recorded a high flow during July (Ist 10 daily) of 2006-07 while other sites recorded normal flows.

Udaipur during 3rd 10 daily period of January 1976-77 and also Ist 10 daily period of Aug2010-11 recorded high flows while other sites recorded normal flows during this period. The abnormal high value at Udaipur site may be due assessment made from the rating curve by CWC instead of actual discharge observation.

Benzwar though intercepting more than 183% of Udaipur catchment area received nearly equal or less runoff/flows as compared to Udaipur during the lean period of 1978 -79 to 1980-81.



High flows were noticed at Benzwar during July 1988-89 (3rd ten daily period) of 1988-89 and Jan (3rd 10 daily period) of 1989-90.

Broadly, it was noticed from the above plots that trend on 10 daily basis at all the three sites were similar and identical. But Gulabgarh flows do not match with flows recorded at other sites. The specific yield at Gulabgarh even do not match with the specific yield of other G&D sites (next para). Benzwar G&D site data also suffers from observational error as indicated in earlier/above para. Thus it is felt that under the present conditions, the observed data of Udaipur site is consistent and reliable. This will be verified at latter date when sufficient site specific data is collected. However, the discrepancies noted and missing data for Udaipur site have been corrected by using the regular data infilling procedure before utilization in the present study. The modified and gap filled discharge data of Udaipur G&D site is at Annexure I.

7.2.7 Specific yield at G&D sites

Specific yield of annual observed flow at G&D sites are compared to know the variations in the yield of the basin with catchment area. The annual average yield at Ghousal, Miyar Nala, Udaipur, Tandi, Gulabgarh and Benzwar sites are computed below in the table.

Table 7.11: Specific Yield at G&D Sites

S. No. Name of G&D

site Catchment

area, sq km Annual avg. Flow, MCM

Specific yield mm

1 Ghousal 2465 3422 1338

2 Miyar Nala 955 1155 1209

3 Tandi 1653 1808 1094

4 Udaipur 5910 7600 1286

5 Gulabgarh 8526 9126 1070

6 Benzwar 10792 13165 1220

A perusal of the above table indicate low specific yield for Gulabgarh G&D site. The Benzwar site is located downstream of proposed Dugar HEP site. The data at these sites appears inconsistent and the same have been corroborated with double mass curve analysis carried out in earlier paras.

The monthly and annual specific yield and their details are given in Annexure VII to Annexure XII.



7.2.8 Quality of Data

An examination of the above paras and analysis/studies carried out to assess the consistence and reliability of data available at G&D sites indicates that Gulabgarh data is inconsistent and unreliable as the flows recorded at this site exhibit erratic behavior/trend i.e the observed flows are ever less than Udaipur (although intercepted area is much more). This can be seen from specific yield computation also.

Similarly the flows observed at Benzwar site are also less than flows recorded at Udaipur G&D site in several years (refer to earlier paras).

It is only Udaipur data which shows consistency. The data observed is considered reliable as seen from the specific yield of Udaipur. The same is proposed to be utilized for the proposed study. The missing data of Udaipur and erratic flows have been filled/modified as per standard infilling techniques. The original observed and modified/filled in data at Udaipur G&D site is available in Annexure-IA and Annexure-I.

7.2.9 Snow studies

Long term observed discharges are available at Udaipur G&D site (CA = 5910 Sq.km) for the period 1974-75 to 2011-12. The snowfed area is appx. 3758 Sq.km. As such an assessment has been carried out to assess the snowfed contribution in observed flows at this site with details as under:-

It has been indicated in earlier paras that base flow regime is observed during the period of October to March. The lowest flow observed during this period is considered as above flow in each 10 daily/ monthly period.

The period June to September is considered as monsoon period. Efforts were made to draw isohyetal curve and Thiessen polygon for assessment of catchment rainfall. Since the locations of rain gauge stations are not evenly distributed and are nearby, so this study could not be carried out. As such arithmetic average method has been utilized to estimate catchment rainfall (tentatively).

Concurrent rainfall data of two stations viz Gondla and Koksar for the period 1974-75 to 2000-01 on monthly time step with Udaipur G&D site data have been considered for the study. The rainfall data availability of third rain gauge station viz Keylong is meager. Even during the period of consideration, some rainfall data is missing. As such only such period where concurrent rainfall and runoff data are available at these stations is used in the study. The details are at Annexure-XIIA.



Runoffs have been estimated from this catchment rainfall considering cent-per-cent runoff factor in absence of relevant and site specific data for its assessment as contribution from rainfed area.

Snowmelt runoff has been estimated after deducting the contributions of flow from rainfed area and base flow from observed data.

The snowmelt study in Annexure XIIA has been carried out for the months of April and May only when there is positive contribution of snowmelt and also snow melt occurs. From the available data, it has been noticed that after consideration of concurrent rainfall, only positive snowmelt contribution (in cumec) has been noticed in few years during the month of April and May in the entire data period .

The base flow during the month of April and May (minimum observed) being 51.84 cumec and 72.32 cumec respectively and average being 62.08 cumec.

The average snowmelt rate varies between 0.3 mm/day to 2.7 mm/day during the month of April and May. This transforms into an average snowmelt flow of 17.7 cumec and 119.2 cumec during the month of April and May.

Thus flow due to the rainfall from above snowmelt study is 2.32 cumec (82.08-62.08-17.7) against 43.79 cumec due to rainfall in month of April. Similarly the average flow in May being 40 cumec and 54.61 cumec. The details are in Annexure –XIIA.

A perusal of above snowmelt study reveals that the study now being carried out considering the 100% runoff factor and estimation of snowmelt contribution may not be realistic. The study has been carried out considering an average base flow during the period. Though the estimated runoff during the month of May matches with observed flows as compared to assessed runoff during April yet consideration of cent-per-cent runoff factor needs verification with observed concurrent reliable rainfall data before utilisation. As such this snowmelt study has not been considered /utilized presently. The observed flow collected at G&D site has been utilized for carrying out the yield assessment study for Dugar HE Project.

7.3 WATER AVAILABILITY The assessment of water availability at the diversion site of any hydro-electric project is very important study. Due care should be taken while computing the flow series at the project site. Long-term observed flow data at any hydro-electric project site are rarely available. The flow series at the diversion site may be computed either by developing a rainfall runoff model and corresponding long term runoff series or by transferring the long-term observed flow data from nearby



G&D site on the same river using catchment area and rainfall proportion. The flow data of the G&D site used for the study is required to be validated and any inconsistency in the data may be corrected before transferring it to project site.

The location of raingauge stations and their data availability in the region is such that it is difficult to compute monthly catchment rainfall for G&D site and proposed project location for utilization in rain fall runoff model. Further, approximately 55% of catchment area is covered under permanent snow cover. As such, rainfall runoff model could not be developed. So Assessment has to be carried out based on either developing runoff-runoff model (in case flow extension is required) or by transposition of observed flows utilizing catchment and rainfall proportion. It is reiterated that long term observed discharge data is available in the catchment upstream of the proposed Dugar HEP site at Udaipur site.

The flow of river Chenab is observed at Udaipur G&D site by Central Water Commission. Long term 10-daily observed flow series is available at this site from 1974-75 to 2011-12 (38 years). No extension of data is required for carrying out simulation studies. The discharge data of Udaipur G&D site is consistent and reliable as indicated in earlier paras. The proposed Dugar HE Project is located downstream of Udaipur Gauge & Discharge site. The catchment area ratio of Dugar HEP (7823 Km2) and Udaipur G&D site (5910 Km2) is 1.32. The observed 10-daily flow at Udaipur for the period 1974-75 to 2011-12 has been considered for the computation of long-term flow series at Dugar HEP. Since the catchment area of proposed project and Udaipur G&D site lays in same hydro-metorological region, the flow characteristics at the Dugar site are be considered to be same as Udaipur site for all practical purposes. Keeping in view the above facts and due to non-availability of sufficient rain gauge stations for assessment of catchment rainfall for Udaipur G&D site and Dugar HEP site, the 10-daily observed flow series at Udaipur G&D of CWC for the period 1974-75 to 2011-12 has been utilized for the present study and transferred to Dugar diversion site in catchment area (direct) proportion. The same is given in Annexure XIII.

7.3.1 Site specific data comparison

DHPL had established a G&D/ hydro meteorological site at the proposed Dugar diversion site since Sept 2011. Daily discharges (using float method) are available for the period Sept 2011 to Aug 2012 (12 months and available in Table 11).

An examination of the observed Dugar site specific data during the period of December 2011 to April 2012 reveals that constant flows were noticed/recorded for several days in each months i.e. during December 2011 it is 43.34 cumec and going to 54.45 cumec during April 2012 (for several days). This aspect was discussed in detail with DHPL who clarified that constant discharges during these periods may be due to non-measurement of flow discharges. No observer/human



being stays at the site in this period due to extreme harsh climatic conditions i.e. low temperature and heavy snowfall. The assessment of discharge thus has been estimated/carried out based on the remotely sensed data from water level recorder. Since it was first year of observation, efforts have been made now (by DHPL) to collect real time data both through an observer and also through remote sensing techniques from this year. The earlier assessed data will be modified/ rectified based on observations being carried during the ensuring year.

The computed flows (average and concurrent period) based on the Udaipur G&D transposed data for the concurrent period was plotted with observed flows at Dugar HEP site. A perusal of the plot below reveals similar identical trend except during the third ten daily period of July 2012 when the project site had experienced a heavy flood. During non-monsoon period, the trend between computed and observed flows is identical.

Figure 7.60: Comparison of derived series with observed data



Table 7.12: Daily Observed Discharge Record of Chenab River in at Dugar HEP

(Unit - m3/s)

7.3.2 Max., Min., Average, 50% and 90% dependable flow at Dugar diversion site

The 10-daily flow summary of water availability series (1974-75 to 2011-12) computed at Dugar HEP diversion is given below in the table and chart. The annual flow with 50% and 90% dependable flows are found to be in year 1980-81 and 1993-94 respectively. The details of the 10-daily flow in 50% and 90% dependable year are also given below.



Table 7.13: 10-Daily flow summary at Dugar HEP (Unit - m3/s)



Figure 7.61: 10-daily max, min and average computed flow at Dugar HEP

Figure 7.62: Flow pattern in 50% and 90% dependable Year at Dugar HEP



Table 7.14: Detail of 50% and 90% Dependable Flow Year

7.3.3 Available Flows

The total available flows at Dugar HEP site from 1974-75 to 2011-2012 is given in ANNEXURE XIII. The average flow duration curve for Dugar HEP site together with the G&D sites in Chenab basin are plotted using ten daily discharges The details are given below in Figure 63 and Table 14 .



Table 7.15: Dependable Flow at Dugar Project and various G&D Sites in Chenab Basin



Figure 7.63: Flow duration curve at Project site (10 daily basis)

A perusal of the above table/figure indicates that discharges observed at Miyar Nala, Tandi and Ghousal are similar. Similarly the flows observed at Benzwar, Gulabgarh, Udaipur and Dugar are alike. However at low percentage of dependability they do not follow the same pattern/match. Further, Gulabgarh flows at low dependability are less than Dugar flows though Gulabgarh intercepts more catchment areas as compared to Dugar HEP. Further, at high dependability the flows are identical at all sites.



7.4 DESIGN FLOOD

7.4.1 General

Estimation of design flood for the design of different type of structures is very significant component of the hydrological study. Proper estimation of the design flood value is very important. The underestimation of design flood may risk the safety of the diversion structure as well as the population and other resources in the downstream of the structure whereas, overestimation of the design flood may result in the increase in cost of structure and wastage of valuable resources.

7.4.2 Design Flood Criteria

As per the Manual on Estimation of Design Flood (CWC, 2001) as well as BIS: 11223-1985, “Guidelines for Fixing Spillway Capacity”, the following criteria applies to determine the design flood of a spillway for a particular category of diversion:

Classification Gross

Storage ( x106 m3)

Hydraulic Head (m)

Inflow Design Flood

Small 0.5 - 10 7.5 –12 100 year return period

Intermediate 10 - 60 12 –30 SPF

Large > 60 > 30 PMF

As Dugar hydro electric project envisages construction of a concrete gravity dam of height of 92 meters above river bed level. Therefore it falls under the category of Large Dam and consequently inflow Design Flood for the project is Probable Maximum Flood (PMF). The same is considered in the present study.

7.4.3 Present Study

The design flood study for the project has been carried out using following two approaches.

a) Hydro-meteorological approach.

b) Probabilistic approach (i.e. flood frequency analysis)

The Hydro-meteorological approach is the most rational method for flood estimation and generally recommended. The short term rainfall-runoff records at project site as well as of upper catchment along with physiographic characteristics



are required for this study. Short term rainfall and runoff data is not available presently at the proposed HEP site..

The Probabilistic approach is the most common procedure for the analysis of annual flood peak data of sufficiently longer duration at a gauged location. This approach can be applied to any type of hydro-meteorological data also, but it is widely used with flood data. Therefore, it is sometimes designated as flood frequency analysis.

7.4.4 Hydro-Meteorological Approach

This approach has been widely used for the estimation of design flood for the medium and large project. The design flood study by this approach takes in to account all the vital physiographic as well as hydro-meteorological parameters of the project basin. The main advantage of this approach as compared to Probabilistic approach is that it gives a complete flood hydrograph which allows making a realistic determination of its moderating effect while passing through a reservoir or in a river reach.

The hydro-meteorological approach needs two basic inputs i.e. unit hydrograph and the design storm to arrive at the required flood. The unit hydrograph is the discharge hydrograph resulting from the 1 cm excess rainfall experienced uniformly over the basin at a uniform rate during a specific period of time. The unit hydrograph may be computed from the project specific observed hydrograph for few high flood events. In absence of the essentially required hydro-meteorological data, a synthetic unit hydrograph is developed using catchment physiographic characteristics.

The design storm input in the present case is Standard Project Storm (SPS) and Probable Maximum Precipitation (PMP). The SPS is the one, which is severe most rain storm on record yielding highest rainfall depth over the catchment or in the meteorologically homogeneous neighborhood of the catchment. The PMP is the one, which is greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of a year i.e. it is the physical upper limit of the rainfall which is not likely to be exceeded in the years to come.

In absence of site specific short interval rainfall runoff records, the procedure for estimation of unit hydrograph given in “Flood Estimation Report for Western Himalaya zone 7, Central Water Commission, 1994” is generally adopted.

The river flood in the Himalayan catchment are constituted by two basic component i.e. runoff contribution from the rain fed part and snow melt contribution snow/ glaciers. Therefore in the present study, the design flood is consisting of two component i.e. flood due to rainfall from the rain fed catchment and flood contribution from snow fed area.

7.4.4.1 Derivation of the Unit Hydrograph



The Central Water Commission (CWC) in association with Indian Meteorological Department (IMD), Ministry of Railway and Ministry of Surface Transport has prepared Flood Estimation reports for small & medium rain fed catchments for efficient hydro-meteorological homogenous sub-zones. These reports illustrate the procedure for derivation of synthetic unit hydrograph based on physiographic parameters. The unit hydrograph for the project rain fed catchment area have been derived as per procedure and guidelines given in the following regional flood report.

CWC sub zone-7 report has been referred for the estimation of the Synthetic Unit Hydrograph Parameters. The details of the same are given below.

i) The following units are consistently used unless specified otherwise

Parameter Unit

Length m

Area km2

Rainfall mm

Discharge m3/s, cumec

Level m

Slope m/km

Hour h or hour

Second s or sec

ii) Physiographic Parameters of Project Catchment

Parameter Symbols Value Unit

Catchment area Arainfed 3365 km2 Asnowfed 4458 km2

Length of longest stream L 238.25 km Length of the stream from CG Lc 91.56 km Equivalent stream slope S 8.64 m/km

The lowest elevation of the project basin is nearly 2015 m. Heavy snowfall is reported in the basin during winter and project site/ catchment become inaccessible. The permanent snow line elevation during storm conditions for the purpose of design flood study have been considered at 4500 m based on the available regional information. The details are available in earlier paras.

The catchment area below 4500 m elevation is considered as rain fed. The physiographic parameter of the rain fed catchment has been used for the derivation of the SUG for the project.



iii) Equivalent slope of stream

Reduced Level

Height above

Datum, Di

Reduced Distance

Length of each

segment, Li

Di-1 + Di Li x (Di-1+Di)

(m) (m) (km) (km) (m) (km x m)1 2015.00 0.00 0.00 0.00 0.00 0.002 2100.00 85.00 12.95 12.95 85.00 1100.843 2250.00 235.00 28.25 15.29 320.00 4894.084 2500.00 485.00 63.20 34.95 720.00 25164.005 2750.00 735.00 97.29 34.10 1220.00 41595.906 3000.00 985.00 135.62 38.33 1720.00 65931.047 3250.00 1235.00 164.62 29.00 2220.00 64382.228 3500.00 1485.00 174.01 9.39 2720.00 25529.929 3750.00 1735.00 181.88 7.87 3220.00 25334.96

10 4000.00 1985.00 197.82 15.95 3720.00 59319.1211 4250.00 2235.00 225.25 27.42 4220.00 115725.0612 4500.00 2485.00 238.25 13.01 4720.00 61393.04

238.25 490370.18

Thus, equivalent stream slope, 8.64 m/km

Sl No.

Total

2)1( )(

LDDL

S iii∑ += −

This is one of the physiographical parameters used in the derivation of Synthetic Unit Hydrograph. The catchment, snow fed area and L section of the river is derived from the Shuttle Radar Topography Mission (SRTM) 90m Digital Elevation Data which is a high- resolution digital topographic database of earth. The same was analyzed in the ARC GIS environment to assess the relevant parameters.

iv) 1-Hour Synthetic Unit Hydrograph Parameters (CWC Manual)

SUG Formula Value Unit



Parameters

tp 2.498*(L*Lc/S)0.156 8.48

hour

qp 1.048*tp -0.178 0.72

cumec

W50 1.954*(L*Lc/S)0.099 4.24

hour

W75 0.972*(L*Lc/S)0.124 2.57

hour

WR50 0.189*(W50)1.769 2.44

hour

WR75 0.419*(W75)1.246 1.36

hour

TB 7.845*tp0.453 20.66

hour

Tm tp+0.5 8.98

hour

Say 9

hour

Qp qp*A 2410

cumec

Where;

A = Total rain fed catchment area up to diversion site in Km2

Ar = Rain fed catchment in Km2

As = Snow fed catchment in Km2

L = Length of longest stream in rain fed catchment in Km

LC = Length of longest main stream from a point opposite to

centroid of the catchment area to point of study in Km

S = Equivalent stream slope in m/Km

tr = Unit duration in hour

tp = Time from the centre of effective rain fall duration to the

Unit Hydrograph (U.G) Peak in hour

Tm = Time from start of rise to the peak of U.G. in hour

TB = Base width of U.G. in hour

qp = Peak Discharge in m3/s/sq.km

Qp = Peak Discharge of unit hydrograph in m3/s

W50 = Width of U.G. measured at 50% of Peak Discharge

Ordinate



W75 = Width of U.G. measured at 75% of peak discharge in hour

WR50 = Width of the rising limb of U.G. measured at 50% of Peak

Discharge Ordinate in hour

WR75 =

Width of the rising limb of U.G. measured at 75% of Peak

Discharge Ordinate in hour

v) Synthetic Unit Hydrograph (CWC Sub Zone-7 report)

Synthetic Unit Hydrograph (SUG) has been plotted using above parameters. The runoff volume of the SUG is checked for the 1 cm depth over the catchment. The ordinates of the SUG are adjusted to give runoff depth of 1.0 cm. While adjusting the ordinates the values of Qp, Tm and TB are not changed.

Table 7.16: Unit Hydrograph Ordinates

Time (hr)

1-hr SUG

(cumec)

Time (hr)

1-hr SUG

(cumec)

0 0 11 600

1 5 12 175

2 10 13 87

3 30 14 40

4 50 15 20

5 125 16 15

6 300 17 10

7 1000 18 7

8 2250 19 5

9 2410 20 3

10 2200 21 0



Figure 7.64: Unit Hydrograph for Dugar H E project

7.4.4.2 Design Storm

IMD New Delhi was requested to carry out the design storm studies so as to assess the 1 day SPS and PMP values for the Dugar site along with the short term storm distribution. The detailed storm study by IMD in Appendix II reveals the following storm depths.

S. No. Return Period of Design

Storm

Value Source

1. 1-day PMP 11.4 cm Report on Design Storm Study by IMD (August

2012) for Dugar HEP

1. 1-day SPS 7.8 cm Report on Design Storm Study by IMD (August

2012) for Dugar HEP

The 1-day PMP and 1- day SPS values for the project catchment have been adopted as supplied by IMD for the present study.



7.4.4.3 Clock Hour Correction

The Clock Hour Correction Factor of 1.15, as recommended by IMD has been adopted for conversion of 1 day rainfall into 24 hour rainfall.

7.4.4.4 Time Distribution Coefficients

Temporal distribution coefficients are used for breaking the 24-hour rainfall value in to hourly rainfall values. These coefficients are estimated from the hourly rainfall information of the severe storms experienced in the past over a basin.

In the present study, the temporal distribution of the 24-hour rainfall has been adopted as supplied by IMD.

Table 7.17: Temporal Distribution

Duration (hr)

Temporal Distribution (%) 24-hr

Design Storm

Duration (hr)

Temporal Distribution (%) 24-hr

Design Storm

0 0.00 13 74.33

1 10.00 14 77.67

2 20.00 15 81.00

3 30.00 16 83.67

4 35.33 17 86.33

5 40.67 18 89.00

6 46.00 19 91.33

7 50.67 20 93.67

8 55.33 21 96.00

9 60.00 22 97.33

10 63.67 23 98.67

11 67.33 24 100.00

12 71.00



Figure 7.65: Temporal Distribution Curve of 24-hour Design Storm for Dugar HEP Site

7.4.4.5 Single Bell

The short term distribution of 24 hours as supplied by IMD is utilized to assess the design flood using single bell. The details are given in Annexure XIV.

Table 7.18: Design Storm for Dugar HEP

Design Storm (cm)

Clock Hour Correction 1.15

Design Storm

1-day 24-hr

SPS 8.6 9.89 PMP 12.6 14.49

7.4.4.6 12 –hr Bells of 24 –hr design storm (Two Bells)

24-hr design storm is distributed in 2-bells of 12 hour (Annexure XV) each in ratio of 0.71 and 0.29 respectively according to the hourly percentages of 24-hour rainfall i.e. temporal distribution as given below in the table.



Table 7.19: 12-hr Bells of 24-hr Design Storm

Type 1-Day Clock-hr

correction factor

24-hr Ratio of 12-hr to 24 hr

rainfall Storm Distribution

(cm)

cm cm I-Bell II-Bell I-Bell II-Bell SPS 8.6 1.15 9.89 0.71 0.29 7.02 2.87 PMP 12.6 1.15 14.49 0.71 0.29 10.29 4.20

The details are given in Annexure XV.

7.4.4.7 Design Loss Rate

Direct surface runoff is the end product of the storm rainfall after the deletion of infiltration in to sub surface soils, initial ground losses and evaporation etc. The design loss rate has been adopted as 0.25 cm/hr as approved by CWC in respect of Seli HE Project in Chenab basin.

7.4.4.8 Critical sequencing of Rainfall Excess

The critical sequencing of the rainfall is done as per the prevailing practice. The highest rainfall ordinate is placed against the maximum UG ordinate and next ranking rainfall against the next ranking UG ordinate. This critical sequence is reversed to obtain the maximum peak. The details of the critical and reversed critical sequencing are given in the Annexure XIV-XV.

7.4.4.9 Base Flow & Snow Melt

The base flow value chosen should be characteristics of the storm season and should preferably be based on observed flood hydrograph. The base flow for the study has been taken as per the recommendation of the sub zone-7 report i.e. @ 0.05 cumec/ sq km of the rain fed catchment area. The base flow contributed from the rain fed area of 3365 sq km is estimated as 168 cumec.

The snow melt contribution has been adopted as per WMO no. 168, equation for heavily forested area adopted from US Army Corps of Engineers for snow/ glaciers melt due to rain.

h =( 0.3+0.012 p)*Tav +1.0 M = Daily snowmelt in mm

P = Daily rain in mm

T = mean daily temperature in °C



The rainfall values have been adopted as 24-hour PMP value of 144.9 mm and 24 hour SPS value of 898.9 mm. The mean temperature of the snow fed area of 4458 km2 has been taken as 2.5 °C and the snow melts contribution have been computed as 314.59 cumec and 243.38 cumec corresponding to PMP and SPS rainfall values.

7.4.4.10 Flood Hydrograph

The direct surface runoff hydrograph has been computed by convoluting 1-hour rainfall excess increments with the ordinates of the 1-hr unit hydrograph. The flood hydrograph of the project basin has been computed by adding base flow and snow melt components to the direct surface runoff. Details of the same are given at Annexure-XIV and XV for 1 bell and 2 bell storm distribution. However, the design flood peaks assessed from both the methods are identical (with minor difference).

The ordinates of the Probable Maximum Flood (PMF) Dugar HE project are given below in the table.

Table 7.20: Design Flood Ordinates at Dugar Dam Site

Time PMF (m3/s) Time PMF (m3/s)

0 482.8 23 5559.8 1 482.8 24 7357.6 2 483.0 25 9033.1 3 483.2 26 9902.1 4 484.2 27 8757.8 5 487.3 28 7107.5 6 494.5 29 5289.8 7 512.6 30 4273.2 8 556.2 31 3329.3 9 658.7 32 2273.4 10 835.7 33 1472.5 11 1244.0 34 811.6 12 1940.2 35 619.8 13 2613.0 36 558.1 14 2967.7 37 524.6 15 2514.7 38 506.8 16 1873.0 39 497.0 17 1223.1 40 491.3 18 1027.6 41 487.5 19 1185.6 42 485.1 20 1905.2 43 483.7 21 2985.4 44 482.8



22 4220.7

Figure 7.66: Design Flood (PMF) Hydrograph of Dugar HEP

The ordinates of the Standard Project Flood (SPF) Dugar HE project are given below in the table.

Table 7.21: Design Flood Ordinates at Dugar Dam Site

Time SPF (m3/s) Time SPF (m3/s)

0 411.6 23 3160.0 1 411.6 24 4374.7 2 411.6 25 5512.8 3 411.6 26 6104.2 4 411.6 27 5324.4 5 412.4 28 4201.1 6 413.9 29 2969.8 7 418.6 30 2299.2 8 425.5 31 1733.9 9 443.2 32 1191.6 10 484.8 33 836.2 11 631.0 34 559.6 12 958.2 35 476.4



13 1283.6 36 448.2 14 1470.0 37 432.2 15 1220.3 38 423.2 16 885.1 39 418.2 17 581.8 40 415.4 18 548.3 41 413.6 19 683.9 42 412.5 20 1054.2 43 412.0 21 1616.4 44 411.6 22 2290.7

Figure 7.67: Design Flood (SPF) Hydrograph of Dugar HEP



7.4.5 Frequency Analysis of Annual Flood Peaks

Flood frequency analyses are used to predict design floods for sites along a river. The technique involves using observed annual peak flow discharge series to calculate statistical information such as mean values, standard deviations, skewness, and recurrence intervals. These statistical data are then used to construct frequency distributions, which are graphs and tables that tell the likelihood of various discharges as a function of recurrence interval or exceedance probability. The reliability of outcome based on this approach depends upon the accuracy and length of observed flood peak series. Flood frequency distributions can take on many forms according to the equations used to carry out the statistical analyses. Four of the common forms are:

i. Gumble Distribution

ii. Log-Normal Distribution

iii. Log-Pearson Type III Distribution

iv. Least Square method

Each distribution can be used to predict design floods; however, there are advantages and disadvantages of each technique. Judgment to adopt the particular distribution/ method is based on the assessment carried out by assessing the Goodness of Fit method. Generally, Chi Square test is carried out in this regards.

In the present case, frequency analysis is done for annual maxima flood peak series available only at Udaipur G&D observation site of CWC for about 39 years keeping in view of the proximity of this site to Dugar HE Project diversion site. The results obtained will be transposed to Dugar diversion site by Dickens’s formula. The detail of annual flood peak series is given below:

Table 7.22: Observed Annual Maxima Flood Peaks at Udaipur Site

S. No. Year Annual Flood Peak (m3/s)


1 16-Jul-74 975.0 21 01-Jul-94 1262.0

2 18-Jul-75 1200.0 22 05-Sep-95 1083.0

3 25-Jul-76 860.0 23 28-Jun-96 806.0

4 15-Jul-77 987.0 24 12-Aug-97 826.0

5 30-Jun-78 1076.0 25 05-Jul-98 1097.0

6 16-Jul-79 993.0 26 20-Jul-99 1382.0

7 14-Jul-80 1116.0 27 01-Aug-00 1199.0





8 29-Jun-81 989.0 28 14-Aug-01 1278.0

9 30-Jul-82 1129.0 29 04-Jul-02 1388.0

10 03-Aug-83 986.0 30 27-Jun-03 1206.0

11 27-Jun-84 785.0 31 09-Jul-04 1177.0

12 13-Jul-85 760.0 32 01-Jul-05 1131.0

13 07-Jul-86 1081.0 33 06-Aug-06 1200.0

14 25-Jul-87 1144.0 34 29-Jun-07 1023.0

15 22-Jul-88 1739.0 35 NA

857.0

16 30-Jul-89 1750.0 36 NA

1220.4

17 25-Jun-90 1235.0 37 06-Aug-10 3785.1

18 20-Jul-91 1238.0 38 28-Jun-11 928.3

19 23-Jul-92 1284 39 03-Aug-12 1008.5

20 08-Jul-93 911

The above flood peaks are annual maxima flood-peak series derived from the flows observed once in a day at the G&D site.

7.4.5.1 Data Check

Annual flood peak series data is required to be checked for its randomness, Chi Square distribution, Jump and outlier in order to satisfy the basic assumption of the flood frequency analysis. There are two basic assumption of the flood frequency analysis i) It is assumed that the natural process is stationery ii) And the series is random

Randomness (Turning point)

A random series is the one in which the value of the next discrete value is unknown i.e. the next value in the series is not predictable. There are number of statistical tests to check the randomness of the data series. In the present case, same has been carried out to check the randomness of the data.



þ =

where p = number of turning points in the AMS.= number of peaks + number of troughs

E(p) = 2/3 (N-2)

Where N = no. of data points in a series .If [þ] < 1.96, series is random at 5% significance level

P = 12+11 = 23 ( from Chart)Ep = 24.667Var (p) = 6.611þ = -0.648 < 1.96Hence, the series is random at significance level of 5%.

Var(p) =

)var()(

ppEP −

902916 −N

From above randomness test it is found that the series is random.

Jump

The presence of any jump may in some cases be detected by simply plotting the time series. The Time-Series graph of the available peak series is shown below. From the figure it may be concluded that there is one jump in the data.

0

400

800

1200

1600

2000

2400

2800

3200

3600

4000

0 5 10 15 20 25 30 35 40 45

Dis

char

ge (c

umec

)

Year

Annual Peak Flood Series at Udaipur Site

Figure 7.68: Time Series Graph, Udaipur Site



Outlier Test

The outlier test has been carried out to assess the outliers in the observed flow peak data series. The result indicates that the flood peak series has an outlier i.e. 3785.1 m3/s.

High outlier threshold Xh = e^(x+kn * )

Low outlier threshold XL = e^(x-kn * )

X Mean of Log series

= S.D of log series

For n = 39Kn = 2.671 From Table (CWC)

High outlier threshold Xh = 2350 > 3785.10(highest value in the series)

Low outlier threshold XL = 542.03 < 760.00(Lowest value in the series)

Hence the series has an outlier

s

s

s

s

.

After eliminating the outlier i.e 3785.1 m3/s (6 August 2010 peak flood value) from the flood peak series, the test are carried out again on data series of 38 flood peak.

Randomness

þ =


E(p) = 2/3 (N-2)


P = 10+11 = 21 ( from Chart)Ep = 24.000Var (p) = 6.433þ = -1.183 < 1.96Hence, the series is random at significance level of 5%.

Var(p) =

)var()(

ppEP −

902916 −N

From above randomness test it is found that the series is random.



Jump

The Time-Series graph of the available 38 years peak series is shown below. From the Figure 7.69 it may be concluded that there is no jump in the data.

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

0 5 10 15 20 25 30 35 40

Dis

char

ge (c

umec

)

Year

Annual Flood Peaks at Udaipur Site

Figure 7.69: Time series graph, Udaipur site

Outlier Test

The outlier test has been carried out to assess the outliers in the observed flow peak data series. The result indicates that the flood peak series has no outlier.

High outlier threshold Xh = e^(x+kn * )

Low outlier threshold XL = e^(x-kn * )

X Mean of Log series

= S.D of log series


High outlier threshold Xh = 1822 > 1750.00(highest value in the series)

Low outlier threshold XL = 656.06 < 760.00(Lowest value in the series)

Hence the series has no outlier

s

s

s

s

.



Chi square Test

The chi square test has been carried out on flood peak series of 38 years using LPT III distribution and Gumbel distribution. It is found that both distributions are fitting on the present flood peak series.

I) LPT III DISTRIBUTION

X 7.00 (Log series)

s 0.1919 (Log series)

Ej 7.6( The number of classes selected are 5)

0-0.2 -α to -0.84162 -α 930.22 8 0.4 0.16

0.2-0.4 -0.84162 to -0.25336 930.22 1041.40 7 -0.6 0.36

0.4-0.6 -0.25336 to 0.25336 1041.40 1147.76 8 0.4 0.16

0.6-0.8 0.25336 to 0.84162 1147.76 1284.94 11 3.4 11.56

0.8-1.0 0.84162 to α 1284.94 α 4 -3.6 12.96Total = 38 25.2

X2 com = 3.32

X2 critical = X2

0.95 = 5.99Since X2

com < X2 critical, the distribution is fitting

Prob of non

Exceedence

(Oj-Ej)2(Oj-Ej)Kt Range Q RANGE Oj

II) GUMBEL DISTRIBUTION

X 1113.43 (observed series)

s 221.7763 (observed series)


0-0.2 -α to -0.84162 -α 926.78 7 0.6 0.360.2-0.4 -0.84162 to -0.25336 926.78 1057.24 8 -0.4 0.160.4-0.6 -0.25336 to 0.25336 1057.24 1169.62 8 -0.4 0.160.6-0.8 0.25336 to 0.84162 1169.62 1300.08 11 -3.4 11.560.8-1.0 0.84162 to α 1300.08 α 4 3.6 12.96

Total = 38 25.2X2

com = 3.32X2

critical = X2 0.95 = 5.99

Since X2 com < X2

critical, the distribution is fitting

Prob of non

Exceeden

(Oj-Ej)2Kt Range Q RANGE Oj (Oj-Ej)



Table 7.23: Details of Tests

S. No. Test

Critical Value for Test statistics

CRITZ

Test statistics

ESTZ

Remark

RANDOMNESS TEST

i. Turning Point Test 1.96 -1.183 Series random at 5% significance

level

ii. Jump No jump detected in time series plot

OUTLIER

i. Upper Limit

Upper limit for high outlier is

XU = 1822 cumec

The highest observed

peak is 1750 cumec

No outlier detected

ii. Lower Limit

lower limit for high outlier is XU = 656,06

cumec

The lowest observed

peak is 760 cumec

No outlier detected

CHI SQUARE TEST

i. LPT III distribution X2

critical = 5.99

X2 com = 3.32

Distribution is

fitting

ii. Gumbel distribution X2

critical = 5.99

X2 com = 3.32

Distribution is

fitting

7.4.5.2 Statistical Parameters of Observed Series

The statistical parameters of the observed annual flood peak series such as mean, standard deviation, coefficient of variance, skewness and kurtosis are important parameters to judge the behavior of a given extreme event series. These parameters are helpful in finding the fitness of the time series to different probability distributions. The values of these estimated parameters are shown in table below.

Table 7.24: Statistical Parameter

S. No Statistical Parameter

Value

1. Mean 1113.43

2. Standard deviation 221.78

3. Variance 0.2

4. Skewness 0.97

5. Kurtosis 4.95



7.4.5.3 Probability Distribution

In order to model the extreme hydrological flood event, the following distributions are very common. In the present analysis also, these distributions have been used for modeling to assess the extreme flood events.

i. Gumble Distribution

ii. Log-Normal Distribution

iii. Log-Pearson Type III Distribution

iv. Least Square method

The outcome of these distributions is shown in the Table 24 below. The Detailed calculation has been annexed at Annexure-XVI.

Table 7.25: Result of Flood Frequency of Annual Observed Flood Peaks of Udaipur

SL.No. Return Period Gumbel Log NormalLOG Pearson Typ-III Least Square

1 2 1091 10832 5 12893 10 1447 1405 14354 20 15105 25 1632 1560 1558 16136 50 1769 1669 17467 100 1906 1728 1778 18778 200 18869 500 2245 1950 2020 218110 1000 2357 2012 2141 2311

The flood estimated for the various return periods in the table above are for the annual observed flood peaks at Udaipur. In order to compensate for the effect of the instantaneous flood peak (annual), the estimated flood values above are increased by 25 % in magnitude. This percentage increase is a figure generally used for Himalayan region where diurnal variation in the river flow is significant in view of the substantial contribution of snow-melt component in the total flow generated from the basin particularly in the summer.

Table 7.26: Result of Flood Frequency of Annual Instantaneous Flood Peaks of Udaipur



The flood peaks for different return periods at Udaipur site are being transposed to Dugar diversion site by giving due consideration to variation in catchment area.

The Dickens’s formula 4/3CAQP = has been used for transposition of flood

values. The detail is shown below: QSHEP = ( ADugar / AUdaipur ) 0.75 * QUdaipur

where:

ADugar = 7823 km2, catchment area for Dugar diversion site

AUdaipur = 5910 km2, catchment area for Udaipur site

QUdaipur = Instantaneous Flood discharges at Udaipur site

The transposed flood peaks at Dugar diversion site is shown in the Table 7.27 below:

Table 7.27: Different Return Period Floods at Dugar Diversion Site



7.4.6 Comparison of Flood by Different Approach

The design flood at Dugar site has been estimated by flood frequency analysis of annual observed flood peaks of 38 years and hydro meteorological approach. A comparison of flood peaks assessed by different approaches is given below:

Table 7.28: Comparison of Design Flood by Different Approach at Dugar HEP Site

S. No. Return Period (Year)

Flood peak (cumec)

Hydro-Met. Approach

Frequency Approach

1 25 - 2517 2 100 - 2939 3 500 - 3463 4. 1000 - 3635 5. SPF 6104 6. PMF 9902 -

7.4.7 Earlier Flood Studies in the Basin

There are several existing and planned project in Chenab basin in the state of Himachal Pradesh and Jammu & Kashmir. The flood studies for these projects have been approved by CWC. The detailed studies for these projects were carried out by several agencies basedon available extensive data including site specific data. The approved design floods for various projects in the Chenab basin are as under.

S. No. Project Name

Catchment Area Design flood Status

Km2 m3/s 1 Dul hasti 10500 8000 Completed 2 Baglihar 17325 16500 Completed 3 Seli 6053 8086 Proposed 4. Ratle 14209 13814 Proposed 5. Kirthai-1 8530 9140 Proposed 6. Such khas 6588 9046 Proposed

Kirthai –I is approved by CWC recently and intercepts an area of 8530 km2.The approved PMF is 9140 cumec. The estimated flood for Dugar HEP (located upstream of Kirthai-I) is thus in conformity with CWC approved flood of proposed downstream project.



7.4.8 Conclusion

The flood peak results at Dugar diversion site shown in Table 7.28. The flood peaks worked out based on hydro-meteorological approach is always considered to be reliable than those arrived by frequency approach. Therefore, flood peaks derived by the hydro-meteorological approach are proposed for the planning purpose.

7.5 DESIGN FLOOD FOR RIVER DIVERSION WORKS The river diversion works during construction generally are planned for the non-monsoon floods. Generally heavy rainfall is experienced during monsoon (Jun-Sept) and river stages are high in the most of the rivers in India during this period. Nearly 70-80% of the total annual rainfall experienced during this period. However in Chenab basin, heavy precipitation is experienced during the in month of March also. The river flows to lower stages generally during non-monsoon i. e. from October to May. The construction in the river bed is generally carried out during low flows in view of the safety of the man and resources, cost of operation and convenience.

Figure 7.70: Variation of discharge in the river

The Dugar HEP is located at nearly 2015 m elevation where weather is hostile in the non-monsoon period also due to heavy snow fall activity during this period. The catchment is either having good amount of rainfall or snowfall in a particular month. The principal season of snowfall can be taken from December to April months when substantial amount of snowfall occurs in the region. Similarly, principal monsoon months can be taken from June to September. Therefore from the river flow, rainfall and snowfall pattern, it can be concluded that diversion works at project site cannot be executed during snow accumulation period. It is possible

10-DAILY FLOW PATTERN OF CHENAB AT UDAIPUR

0

100

200

300

400

500

600

700

800

I II III I II III I II III I II III I II III I II III I II III I II III I II III I II III I II III I II III

Jun. Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May

10-D

AIL

Y FL

OW

(CU

MEC

)



to execute good amount of project works at diversion site only in monsoon months because of prevailing weather conditions near the diversion site.

Therefore, design flood for Dugar project has been worked out for both the periods and planning may be carried out keeping in view the prevailing weather conditions at diversion site as well as cost of the diversion works in addition to the in-built risk of machinery as well as human life during the project work.

7.5.1 Design Flood Criteria

Since the headwork structure is a barrage, as per BIS: 14815-2000, “Design Flood for River Diversion Works – Guidelines,” the diversion capacity has to be the higher of the two following values and shall be used as design flood for diversion works subjected to condition that construction period is fixed as non-monsoon period:

Maximum non-monsoon flow observed at the diversion site; (OR)

25 years return period flow, calculated on the basis of non-monsoon yearly peaks

If construction is carried out during the whole or monsoon period, then diversion flood is decided based on monsoon flood peaks.

Here the following criteria govern the finalization of diversion flood:

Maximum monsoon flow observed at the diversion site; (OR)

25 years return period flow, calculated on the basis of monsoon yearly peaks

However, assessment have been carried out, both by considering monsoon and non monsoon peak floods.

7.5.2 Data Available

The observed non-monsoon flood peaks for 38- years are available on river Chenab at Udaipur G&D site of CWC located Upstream of Dugar project. The monsoon flood peaks are given in Table 21 in the previous section, and the non-monsoon flood peaks are given in the Table 28 below:



Table 7.29: Detail of Non-monsoon (Oct-May) Flood Peaks, Udaipur

7.5.2.1 Data Check

Non monsoon flood peak series data is required to be checked for its randomness, Chi Square distribution, Jump and outlier in order to satisfy the basic assumption of the flood frequency analysis. There are two basic assumption of the flood frequency analysis i) It is assumed that the natural process is stationery ii) And the series is random

Randomness

A random series is the one in which the value of the next discrete value is unknown i.e. the next value in the series is not predictable. There are number of statistical tests to check the randomness of the data series. In the present case, same has been carried out to check the randomness of the data.

S.No.

Year Annual Flood Peak (m3/s)

S.No. Year Annual

Flood Peak (m3/s)

1 1974-75 259 20 1993-94 264 2 1975-76 309 21 1994-95 204 3 1976-77 350 22 1995-96 310 4 1977-78 285 23 1996-97 398 5 1978-79 264 24 1997-98 307 6 1979-80 225 25 1998-99 409 7 1980-81 362 26 1999-00 501 8 1981-82 264 27 2000-01 452 9 1982-83 403 28 2001-02 531 10 1983-84 438 29 2002-03 453 11 1984-85 285 30 2003-04 426 12 1985-86 268 31 2004-05 488 13 1986-87 219 32 2005-06 300 14 1987-88 404 33 2006-07 455 15 1988-89 425 34 2007-08 331 16 1989-90 360 35 2008-09 260 17 1990-91 213 36 2009-10 263 18 1991-92 426 37 2010-11 477 19 1992-93 211 38 2011-12 363



þ =


E(p) = 2/3 (N-2)


P = 12+13 = 25 ( from Chart)Ep = 24.000Var (p) = 6.433þ = 0.394 < 1.96Hence, the series is random at significance level of 5%.

Var(p) =

)var()(

ppEP −

902916 −N

Jump

The presence of any jump may in some cases be detected by simply plotting the time series. The Time-Series graph of the available peak series is shown below. From the figure it may be concluded that there is no jump in the data.

0

100

200

300

400

500

600

0 5 10 15 20 25 30 35 40

Dis

char

ge (c

umec

)

Year

Non Monsoon flood Peaks at Udaipur Site

Figure 7.71: Time series graph, Udaipur site



Outlier Test

The oulier test has been carried out to assess the outliers in the observed flow peak data. The result indicated the absence of any outliers.

High outlier threshold Xh e^(x+kn * )

Low outlier threshold XL =e^(x-kn * )X Mean of Log series

= S.D of log series


High outlier threshold Xh 696 >531.00(highest value in the series)

Low outlier threshold XL = 162.74 <204.00(Lowest value in the series)

Hence the series have no Outlier

s

s

s

s

Chi square Test

The chi square test has been carried out on non monsoon flood peak series of 38 years using LPT III distribution and Gumbel distribution. It is found that both distributions are fitting on the present flood peak series.

I) LPT III DISTRIBUTION

X 5.82 (Log series)

s 0.2730 (Log series)


0-0.2 -α to -0.84162 -α 267.42 10 2.4 5.76

0.2-0.4 -0.84162 to -0.25336 267.42 314.00 7 -0.6 0.36

0.4-0.6 -0.25336 to 0.25336 314.00 360.58 4 -3.6 12.96

0.6-0.8 0.25336 to 0.84162 360.58 423.40 6 -1.6 2.56

0.8-1.0 0.84162 to α 423.40 α 11 3.4 11.56Total = 38 33.2

X2 com = 4.37

X2 critical = X2

0.95 = 5.99Since X2

com < X2 critical, the distribution is fitting

Prob of non

Exceedence

(Oj-Ej)2(Oj-Ej)Kt Range Q RANGE Oj



II) GUMBEL DISTRIBUTION

X 348.61 (observed series)

s 92.0448 (observed series)


0-0.2 -α to -0.84162 -α 271.14 11 -3.4 11.560.2-0.4 -0.84162 to -0.25336 271.14 325.28 6 1.6 2.560.4-0.6 -0.25336 to 0.25336 325.28 371.93 6 1.6 2.560.6-0.8 0.25336 to 0.84162 371.93 426.07 7 0.6 0.360.8-1.0 0.84162 to α 426.07 α 8 -0.4 0.16

Total = 38 17.2X2

com = 2.26X2

critical = X2 0.95 = 5.99

Since X2 com < X2

critical, the distribution is fitting

Prob of non

Exceeden

(Oj-Ej)2Kt Range Q RANGE Oj (Oj-Ej)

Table 7.30: Details of Tests

S. No. Test

Critical Value for Test statistics

CRITZ

Test statistics

ESTZ

Remark

RANDOMNESS TEST

i. Turning Point Test 1.96 0.394 Series random at 5% significance

level

ii. Jump No jump detected in time series plot

OUTLIER

i. Upper Limit

Upper limit for high outlier is

XU = 696 cumec

The highest observed

peak is 531 cumec

No outlier detected

ii. Lower Limit

Lower limit for high outlier is XU = 162.74

cumec

The lowest observed

peak is 204 cumec

No outlier detected

CHI SQUARE TEST

i. LPT III distribution X2

critical = 5.99

X2 com = 4.37

Distribution is

fitting

ii. Gumbel distribution X2

critical = 5.99

X2 com = 2.26

Distribution is

fitting



7.5.3 Statistical Parameters

The detail of important statistical parameters for the observed non-monsoon flood peaks is given in the Table 7.31 below:

Table 7.31: Statistical Parameter, Non-Monsoon

S. No

Statistical

Parameter

Value

1. Mean 348.61

2. Standard deviation 92.04

3. Variance 0.26

4. Skewness 0.14

5. Kurtosis 2.11

7.5.4 Probability Distribution

In order to model the extreme hydrological flood event, the following distributions are very common applications. In the present analysis also, these distributions have been used for modeling to assess the extreme flood events.

i. Gumble Distribution ii. Log-Normal Distribution iii. Log-Pearson Type III Distribution iv. Least Square

The outcome of these distributions is shown in the Table 7.32 below. The Detailed calculation has been annexed at Annexure-XVII.

Table 7.32: Result of Flood Frequency of Non monsoon Flood Peaks of Udaipur

Return Period Gumbel Log NormalLOG Pearson Typ-III Least Square

2 337 3405 419

10 487 474 48220 51625 564 525 531 55650 621 571 610100 677 616 608 665200 643500 791

1000 865 753 720 845 The non monsoon flood estimated for the various return period in the table above are for the non monsoon flood peaks at Udaipur. In order to compensate the effect



of the non monsoon instantaneous flood peak, the estimated flood values above are increased by 25 % in magnitude. This percentage increase is a figure generally used for Himalayan region where diurnal variation in the river flow is significant in view of the substantial contribution of snow-melt component in the total flow generated from the basin particularly in the summer.

Table 7.33: Result of Flood Frequency of Non Monsoon Instantaneous Flood Peaks

of Udaipur

SL.No. Return Period Gumbel Log NormalLOG Pearson Typ-III Least Square

1 2 421 4252 5 5243 10 609 593 6024 20 6455 25 705 656 664 6946 50 776 713 7637 100 847 770 759 8318 200 8049 500 98810 1000 1081 941 900 1056

The flood peaks for different return periods at Udaipur site are being transposed to Dugar diversion site by giving due considration to variation in catchment area. The

Dickens’s formula 4/3CAQP = has been used for transposition of flood values.

The detail is shown below:

QSHEP = ( ADugar / AUdaipur ) 0.75 * QUdaipur

where:

ADugar = 7823 km2, catchment area for Dugar diversion site

AUdaipur = 5910 km2, catchment area for Udaipur site

QUdaipur = Instantaneous Flood discharges at Udaipur site

The transposed flood peaks at Dugar diversion site is shown in the Table 33 below:

Table 7.34: Different Return Period Non Monsoon Floods at Dugar Diversion Site



The maximum values of non monsoon flood at Dugar diversion site are computed by Gumbel Distribution.

The diversion flood for the monsoon and non-monsoon period may be adopted as 2517 cumec and 870 cumec respectively as per BIS criteria.

7.5.5 Conclusion

The design flood for river diversion works is based on the flow data of Chenab River observed at Udaipur site, having long term observed flow data for 38 years. Therefore, arrived values of 2517 m3/s and 870 m3/s are proposed for planning of diversion works.



7.6 SEDIMENTATION STUDY Dugar HE project is proposed to be planned as run-of the river scheme. Though detailed sedimentation study is not needed for runoff river projects, yet considering the height of diversion structure as 101 m from river bed level, detailed sedimentation study have been carried out to assess the New Zero Elevation and revised Elevation- Area- Capacity as per BIS standard. The detailed sedimentation study is done as per IS: 12182-1987 “Guideline for determination of effect of sedimentation in planning & performance of reservoir” and IS: 5477 (Part 2)-1994 “Fixing the capacities of reservoirs- Methods”. However particle size analysis and petrography of the silt load is necessary for the safety of the turbines as well as in view of operation and maintenance.

As per BIS 12182-1987, full service time for a hydropower project supplying power to grid shall not be less than 25 years while the feasible service time shall not be less than 70 years.

7.6.1 Average annual Sediment Rate

So far, adequate site specific data of sediment load is not available on basis of which the planning for sedimentation would be done. It is a normal practice to consider rate of sedimentation for the stations in the hydro meteorologically similar region.

The suspended silt load data at Udaipur G&D site for the period 2003-04 to 2012-13 has been analyzed. The monthly silt data at Udaipur G&D site is plotted below to indicate the monthly sediment inflow at this site. The details are in Annexure –VIIA. It indicates that heavy sediment load is experienced during the monsoon period while sediment concentration is low during non-monsoon period.



The year wise total suspended silt load at Udaipur site is analysed and based on observed silt data, the silt rate is assessed as 0.058 Ham/Sq.Km/year. The details are indicated in Table 7.35 below:

Table 7.35: Yearly Sediment Rate

Since site specific observed silt data is not available, tentatively sediment study has been carried out based on an annual silt rate of 0.058 Ham/Sq. Km/year for Dugar HEP site. While carrying out the sedimentation study, New Zero Elevation and revised elevation-Area- Capacity curve based on project operation studies have been estimated to assess the MDDL/DSL for the Dugar HEP.



7.6.2 Original Elevation –Area- Capacity curve

The elevation-area-capacity of present diversion site is tabulated below:

Table 7.36: Original Elevation-Area-Capacity at Dugar Diversion Site

Figure 7.72: Original Elevation-Area-Capacity curve at Dugar diversion site

Elevation

Original Area

Original Capacity

m ha ha-m 1 2 3

2015 0 0 2020 2 3 2030 12 64 2040 26 247 2050 37 558 2060 53 1004 2070 75 1641 2080 92 2476 2090 110 3487 2096 123 4187 2100 131 4695 2105 150 5397 2110 169 6194 2114 188 6963 2120 217 8117



7.6.3 Type of reservoir

Figure 7.73: Type of reservoir



7.6.4 Sediment Analysis

The Reservoir sedimentation problem has been classified as serious. Hence variable trap efficiency has been considered for computing sediment volume given in para 1.6.5. The New Zero Elevation after different length of period works out to as given in para 1.6.6.



7.6.5 Trap Efficiency Computation

7.6.6 Estimation of New Zero Elevation

New zero elevation after 25, 50 years and 70 years have been computed by Empirical area Reduction Method as 2060.54 m, 2080.34 m and 2084.30 m respectively

Revised Area Capacity Curve and calculation after 25, 50 and 70 Years of sedimentation are given in Annexure XVIII.

The FRL provided is 2114 m while MDDL is 2102.06m.

7.7 LIMITATIONS OF STUDY The study has been carried out based on hydro meteorological data as available in the region in absence of site specific data. DHPL has already installed a hydro meteorological station at Dugar HEP diversion site since Sept 2011. When sufficient site specific data is available, it is suggested that hydrological provisions may be reviewed.



ANNEXURES



ANNEXURE IA – 10 daily discharge data at Udaipur G&D Site

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