LUHRI H.E.PROJECT (3X155=465MW) HIMACHAL PRADESH

1. INTRODUCTION Luhri Hydroelectric Project located in Shimla district of Himachal Pradesh

envisages utilization of waters of the river Satluj for power generation on a run

of the river type development, harnessing a head of about 127 m.

The project with a proposed installation of 465MW (3x155MW) would afford

an annual energy generation of 2037.15 MU in a 90% dependable year. The

tariff from the project at present day cost would be Rs 1.66.

The diversion site is located at Latitude 30 15' North, Longitude 77 15' East.

The dam site is about 80 km from Shimla, the state capital.The nearest rail

head and airport are located at Shimla.

2. SCOPE OF WORKS The Luhri H.E.Project envisages construction of

A 60m high(above river bed) straight gravity type concrete dam

across river Satluj to divert 596 cumecs of discharge;

Four numbers desilting chambers of length 580m(L) and size

14m(W) x25m (H) to remove silt particles of size 0.25mm and

above;

A 15.50 km long and 10.50m diameter head race tunnel terminating

in a surge shaft;

A 147 m high 37 m diameter open to sky surge shaft;

Three no's 220m long, 5.55m diameter pressure shaft;

an underground powerhouse having an installation of 3 Francis

driven generating unites of 155MW each operating under a net

head of 108m.

100m long and 10.50 m diameter tail race tunnel to carry the power

house releases back to the river;

It is proposed to evacuate the power generated at Luhri Project by

Looping in Looping out of 400 kV Jhakari-Hissar D/C line with

TRIPPLE SNOWBIRD conductor at Luhri. As per recommendations

made by PGCIL in their report on master plan for evacuation of power

from various projects located in Satluj basin, this line is proposed to

be LILOed at Rampur.

The Salient features of the project are given at Annex-I and a layout map at Plate I.

3. HYDROLOGY

The catchment area of river Satluj at the proposed dam site is about 52403

sq. km. The water availability for the project has been considered on the basis

of 10-daily discharge series at Suni and Rampur. The long term series at

Luhri dam site has been developed on proportionate catchment area basis

from these two sites. The computed series has been utilized for Power

Potential Studies. The design flood has been assessed as 6579 cumecs.

4. POWER POTENTIAL STUDIES

The computed inflow series for 31 years viz 1972 to 2003 has been

considered in the assessment of a power benefits from the project. As per

GOI notification for tariff the year 1997-98 corresponds to 90% dependable

year. An installation of 465 MW comprising 3-generation units of 155 MW has

been proposed. The energy availability from the project in a dependable and

an average year has been summarized below:

Particulars Dependable year

Annual Energy Generation

Annual Energy Generation (GWh) 2037.15

Annual Load Factor (%) 64%

Generation during Lean Flow Season (Dec.-Feb.)

Energy Output (GWh) 208.64

Load Factor (%) 24.15

The design energy for tariff at 95% availability in a 90% dependable year has

been worked out at 2037.15 GWh.

A pondage of 67.80 mcm has been provided in the diversion dam which

would enable the station to operate as peaking station.

5. POWER EVACUATION ASPECTS

It is proposed to evacuate the power generated at Luhri Project by Looping in

Looping out of 400 kV Jhakari-Hissar D/C line with TRIPPLE SNOWBIRD

conductor at Luhri. As per recommendations made by PGCIL in their report

on master plan for evacuation of power from various projects located in

Satluj basin, this line is proposed to be LILOed at Rampur.

6. ENVIRONMENTAL ASPECTS The project is located in middle area of upper Satluj valley. Most of the land

falls under the category of forest land. Based on assessment of

environmental impacts, management plans have to be formulated for

Catchment Area Treatment, compensatory afforestation and other

environmental issues. These issues would be addressed during the

investigation for DPR.

7. ESTIMATE OF THE COST The project is estimated to cost Rs. 1930.84 crores including IDC at January

2004 price levels. The preliminary cost estimate of the project has been

prepared as per guidelines of CEA/CWC. The break down of the cost

estimates is given below:

Civil works : Rs. 1139.67 Crores

Electro Mechanical works : Rs. 461.73 Crores

Sub total (Generation) : Rs. 1601.40 Crores

Transmission works : Rs. 10.86 Crores

Total (Hard Cost) : Rs. 1612.26 Crores

Interest During Construction : Rs. 318.58 Crores

Grand Total : Rs. 1930.84 Crores

8. FINANCIAL ASPECTS

As indicated above, the Luhri Hydro-electric project with an estimated cost of

Rs. 1930.84 crores (including IDC of Rs. 318.58 crores) and design energy of

2037.15 GWh in a 90% dependable year is proposed to be completed in a

period of 6 years. The tariff has been worked out considering a debt-equity

ratio of 70:30, 16% return on equity, annual interest rate on loan at 10% and

12% of energy as Free power to Home State available after losses. The tariff

for first year and levellised tariff works out Rs. 2.10 /kWh & Rs. 1.66 /kWh

respectively.

9. CONCLUSIONS Luhri hydroelectric project involves simple civil works and could be completed

in 6 years. The project would afford design energy of 2037.15 GWh in a 90%

dependable year. The cost per MW installed works out Rs. 3.92 crores. The

Preliminary Feasibility Report indicates that the scheme merits consideration

for taking up for Survey & Investigation and preparation of DPR.

LUHRI HEP(465 MW)

I

SALIENT FEATURES OF THE PROJECT LOCATION State Himachal Pradesh District Shimla River Satluj Vicinity Diversion dam site near Village Nathan & Power House site near Village Chaba about 80 km from

Shimla (HP). Geographical co-ordinates 7715- 7730 3015-3125 SOI Toposheets 52E/7 HYDROLOGY Catchment area at diversion site. 52403 Sq km Average runoff in 90 % dependable year 9548 MM Average runoff in 50 % mean year 121131 MM DIVERSION DAM Type Concrete Gravity Full reservoir level El 770.00 m. Maximum pond level El 773.00 m. M D D L El 728.00 m River Bed Level at Dam site El. 709.80m.

LUHRI HEP(465 MW)

II

SEDIMENTATION CHAMBERS No. of sedimentation chambers 5 Width 16m. Depth 35.5m. Length 705 m. Particle size to be arrested +0.25 mm. Design discharge 586.00 cumecs. Flow through velocity 0.3 m/s HEAD RACE TUNNEL Type Horse shoe, concrete lined Diameter 11 m finished. Length 15500 m. Design discharge 586 cumecs. SURGE SHAFT No. One Type Restricted Orifice ( Underground ) Diameter 52.00 m

LUHRI HEP(465 MW)

III

Orifice Dia. 5.54 m PRESSURE SHAFTS No. 3 Type Circular steel lined (Underground) Diameter 6.35 m ( Finished ) Length 220.00 m each Steel Liner Type ASTM 537 Thickness Varies from 15 to 35 mm POWER HOUSE / TRANSFORMER HALL CAVITY Type Underground Installed capacity 465 MW(3 x 155 MW) Size of machine hall 123m (L) X 21m (W) x 51m(H) Size of transformer hall 78m (L) X 16m (W) x 25m(H) Gross head 128.00m Net head at 586 cumecs tunnel 88.00 m discharge

LUHRI HEP(465 MW)

IV

ELECTRO- MECHANICAL EQUIPMENT TURBINES No. and type 3 nos., Francis turbines Design head 88.00 m Design discharge 195.33 cumecs TAIL RACE TUNNEL Size & Type 11.00 m dia. Horse shoe shape Length 150 m POWER GENERATION Installed capacity 465 MW Annual generation -90% dependable year 1825.13 GWH -50% dependable year 2060.50 GWH COST ESTIMATE ( Rs in crores) Civil Works 1235.70 E-M Works 461.73 Transmission 10.86 Total base cost of Project (January 2004 price level) Rs.1708.29 Crores

LUHRI HEP(465 MW)

V

FINANCIAL ASPECTS Cost per MW of installed capacity Rs. 3.49 Crores Sale rate per unit (at bus bar) 90 % dependable year

First year Rs. 2.41 per unit Tenth year Rs. 1.80 per unit Levellised tariff for 35 years Rs 1.89 per unit

( 12 % discount rate)

LUHRI HEP (465 MW)

I.1

CHAPTER-I

SUMMARY

1.1 GENERAL PROJECT FEATURES

1.1.1 GENERAL

Luhri Hydroelectric Project located in Shimla district of Himachal

Pradesh, is a run-of- the river type development proposed to harness

the hydel potential of river Satluj between Luhri and Chaba villages.

The project envisages construction of a 60m high (above river bed)

concrete gravity dam on the river Satluj near village Nathan for

diversion of a design discharge of 586 cumecs, through four intakes

and underground desilting arrangement into a 15.50 km long, 11.00m

finished diameter head race tunnel on the right bank of Satluj river. The

tunnel terminates in a 52 m diameter open to sky surge tank. The

water from surge tank shall be further conveyed through three no's,

each 6.35 m diameter, 220 long steel penstock to three generating

units in an underground power house at Chaba. A gross head of 128 m

is available at the power station, which shall be utilized to generate 465

MW (3x155MW) of power.

1.2 MAIN COMPONENTS OF THE PROJECT 1.2.1 River diversion works

For the construction of the dam and appurtenant works, the river

diversion is proposed to be done through a diversion tunnel, located on

the left bank of river, capable of carrying non-monsoon flood of 1267

cumecs. Partly constructed works of the concrete dam on the left bank

and in the river portion shall be allowed to be over topped during

monsoon period.

LUHRI HEP (465 MW)

I.2

Coffer dams shall be constructed up-stream and down-stream of the

dam axis near the inlet & outlet portals of the diversion tunnel every

year after the monsoons.

1.2.2 Diversion dam It is proposed to construct a straight gravity type concrete dam, 60 high

(above river bed) near Nathan Village to divert 586 cumecs of

discharge.

The full reservoir level and the minimum draw-down level will be at El

770 m and 728 m respectively. The diurnal pondage afforded by the

dam would be 12.45 MM3 . The water spread of the reservoir does not

involve any rehabilitation problem, as the area submerged is barren

land without any habitation.

1.2.3 Intake Structure The intake structure comprising five intakes, proposed on the right

bank of river shall be designed to handle a discharge of 733 cumecs.

1.2.4 Desilting arrangement

An underground desilting arrangement has been proposed on the right

bank of river to exclude silt particles down to 0.25 mm size from the

water before it enters the head race tunnel. The arrangement

comprises five parallel compartments each consisting of chambers

705 m long, 35.50 m high (including 7.50 m hopper portion) and 16 m

wide.

LUHRI HEP (465 MW)

I.3

1.2.5. Head race tunnel

The head race tunnel, from the junction point at link tunnels from

desilting chambers to the main surge tank, is 15.50 km. long and 11 m

diameter horse shoe in section. The tunnel diameter is based on

techno-economic studies for a discharge of 586 cumecs with a flow

velocity of 5.81 m/sec.

1.2.6 Main surge tank

The main surge tank, located at the intake of the penstock at 15.50 km

from the 0 RD of head race tunnel, will be 52 m dia and 147.00 m high

with a restricted orifice and two horizontal expansion galleries 10 m D-

shaped and 150 m long each. A 6.50 m D-shaped adit is proposed at

El 670.00 m to approach the bottom of the surge tank to facilitate

construction. The upper expansion gallery shall be approached for

construction through a 6.50 m D-shaped adit.

1.2.7 Pressure shaft tunnels

Three penstock tunnels, each 220 m long and 6.35 m dia would take

off from the surge tank at an angle of approximately 90 to the

horizontal. These would be lined with high tensile steel corresponding

to ASTM-A-537 varying in thickness from 15mm near the penstock

intake to 35mm at the power house end. Each penstock will feed one

of the three generating units. A spherical valve has been provided in

each penstock branch to enable closing of penstock penstock

whenever required.

LUHRI HEP (465 MW)

I.4

1.2.8 Power house An underground power house of internal dimensions 123 m x 21 m and

51 m high would be located about 130m below the natural surface

level. The power house will have an arched roof with concrete lining

and shall house three generating units, each of 165 MW capacity. The

transformer and underground switch yard (78 m x 16 m x 25 m) are

located downstream of the power house cavern. Shotcrete and rock

bolting at suitable spacing will be provided in these caverns.

Two utility tunnels taking off from the tail race tunnel shall be provided

to approach the bottom portion of the power house and shall facilitates

the excavation of the machine hall, transformer gallery and tail race

surge chamber. To approach the top of the machine hall as also the

top of transformer gallery and tail race surge chamber, an adit is

proposed to be constructed with its portal at EL. 668 m. This adit

shall be used for construction of arch portion and other works from the

top.

1.2.9 Tail race tunnel

The tail race tunnel with 11 m horse shoe section, 150 m long will be

provided to carry the discharge from four draft tube tunnels emanating

from the power house.

1.3 STUDIES UNDERTAKEN

1.3.1 Various alternatives

Four potential diversion sites have been identified, namely Luhri-I,

Luhri-II and Dam site-III & IV. Generally good conditions exist for dam

construction at Nathan dam site, which may be considered as a good

site for a concrete gravity dam. The rock mass is composed of strong

LUHRI HEP (465 MW)

I.5

to very long quartz phyllite, with relatively poorly developed cleavage.

Continuous, horizontal structures are apparent on the south side of the

river, with essentially massive quartzite interrupted by widely spaced

planes, which are assumed to be tight cleavage planes. In addition,

near vertical joint surfaces were observed to cross the river valley

obliquely. These usually display a steep dip in the upstream direction

and produce a blocky structure in the valley slopes. The rock may be

suitable for use in the production of aggregates for concrete purposes.

1.3.2 Hydrological Studies (a) Hydrology: - Collection of Hydro meteorological data

i) Discharge data of Satluj river at Rampur ii) Discharge data of Satluj at Suni iii) Discharge data of Satluj at Kasol

(b) Water availability studies

i) Computation of 90% availability and 50% availability discharges.

ii) Flow duration curve iii) Power generation in a 90 % and 50 % dependable years

(c) Flood studies

i) Flood frequency analysis for Monsoon flood ii) Flood frequency analysis for Non-monsoon flood.

1.3.3 Initial Environmental studies

i) Digitisation of maps (toposheets) with permission of SOI. ii) Satellite imageries as required from NRSA.

LUHRI HEP (465 MW)

I.6

iii) Processing of satellite data for the area of interest by the

consultant. The procedure adopted for processing will be: - a) Multi-spectral LISS(23.5m resolution) and Single Band PAN(

5.8 m resolution) data. b) Land use classification for the area will be carried out after

geo-referencing the satellite data. c) Land use classification consisting of the following

1. Vegetation crown, Cover (Tree canopy) 2. Built up areas? Rocky outcrop etc. 3. Agricultural land (Land on which Agriculture is being

practised currently). 4. Vegetation density classification (Low, medium, high). 5. Water bodies 6. Barren land 7. Any of the peculiar land use category, as per local

scenario. 8. Land use pattern. 9. Vegetal cover/density 10. Approximate population density.

1.4 COST AND FINANCIAL ASPECTS

The estimate of costs has been prepared in detail to arrive at the total cost of the project. The estimates are based on the prices prevailing in January-2004. The detailed estimate of cost of civil works is based on the conceptual layout plan and preliminary designs of different components of the works. The layout of different works have been taken after considering various alternatives and economical layout have been adopted. For carrying out preliminary design, detailed analysis of rates of different items of works have been prepared as per Guidelines of CWC (Guidelines for preparation of project estimate for river valley projects- March 1997). The rates for hydraulic gates, hoists and cranes etc. are

LUHRI HEP (465 MW)

I.7

based on the prevalent market rates for such works. Apart from main civil works, the provisions under various other sub-heads are also based on the Guidelines of CWC. Cost of generating plant and equipment is based on current budgetary prices of plants for similar equipment for other projects Provisions for other items like establishment, audit and accounts etc. are as per norms of CEA. The total cost of the project at January 2004 price level excluding escalation, IDC and Financing Charges works out as under:

Civil Works

1235.70

Crore

Electrical Works

461.73

Crore

Transmission

10.86

Crore

Total

1708.29

Crore

The cost per MW of installed capacity works out to Rs. 3.49 Crore (at January 2004 price level). Thus, the cost per MW for this project is quite low, making the project very attractive.

1.5 RECOMMENDATION

Detailed survey's as per CWC guidelines are to be done before

detailed project report to firm up the various components.

LUHRI HEP (465 MW)

I.8

Detailed geological investigations I,e,drill holes at dam site to confirm

the depth to bed rock, drift at various adits and other geological

investigations as per CWC guide lines.

LUHRI HEP

1

CHAPTER II

BACKGROUND INFORMATION

2.1 GENERAL INFORMATION ABOUT THE RIVER/BASIN/SUB-BASIN

River Satluj rises near Rakas-Tal lake which is fed by lake Mansarover at

about 4570m above mean sea level between Rakas-Tal and Shipkilla,

near the Indian border, the Satluj river takes a North-Westerly course for

a length of about 320 Km in the Tibetan province of Nari-Khorsam. The

Satluj is joined by several tributaries in Nari-khorsam such as Changchu,

Drama Yankti, Chonak, Manglan, Transuo, Summa, Trap etc.

Immediately after entering the Indian territory near Shipkilla, the river

takes a south-westerly direction on its way to Bhakra gorge about 320 Km

away after crossing, which it emerges into the plains of the Punjab. The

Satluj crosses the Great Himalayas at a point where the range bifurcates.

At Rampur, it crosses the Dahuladhar range then traverses through a

series of successive Shivalik ranges and the Naina Devi range, where the

Bhakra dam is situated, is the last of the series. Between Suni and

Dehar, the river takes a somewhat north-westerly direction. After Dehar,

the river turns in a south -westerly direction to reach the foot of Naina

Devi range. The Naina Devi range deflects the river again in a north-

westerly direction when it flows parallel to the range for about 32km

before cutting through it at Bhakra gorge.

The principal tributaries of the Satluj below Shipkilla are the Spiti,

Kashang, Baspa, Bhaba, Nogli, Kurpan, Nauti, Sholding, Sorang, Bharari,

Ali and Ghambar khad.

Numerous glaciers large and small, drain into the Satluj at various points

LUHRI HEP

2

on its course. East of Mansarover and feeding its principal source are the

glaciers of the Ganglug Gaungni, the southern glaciers of the Gauglung

Gangni, glaciers of Kailash flow into the Satluj through the lake of Rakas

Tal, The Northern glaciers of peak Kamer also contribute to the streams.

The glaciers of peak Riwa phargul that stands in the Satluj catchment

also flow into it. There are many Himalayan glaciers draining

into its tributaries. The Baspa and many more from the direction of the

Bara-Lacha pass from the watersheds of the Chenab and Beas.

The fall of Satluj from its source to the plains of India is very uniform. The

height of the bed is about 4570m near Rakas-Tal, 2530m near Shipkilla,

915m at Rampur, 416 m at Bilaspur and 350m at the Bhakra Dam site.

The total catchment area of the Satluj above the Bhakra dam site is about

56875 Sq.km (21960 Sq.miles) and above the Nathpa diversion site is

about 49820 Sq.km (19235 Sq.miles) from Bhakra to Nathpa, 148 Km on

a straight line and 193Km by river, the drainage area is comparatively

narrow with an average width of about 35km. This part of catchment has

an area 7055 Sq.km and above Nathpa the catchment is considerably

wider than below it. The river Satluj drains an area of about 50880 Sq.km

(196745 Sq.miles) at Rampur discharge site.

A gross fall of 2180m is available in the river bed from Shipkilla to Bhakra

in an length of about 320 Km and about 990m from Shipkilla to the

Shongtong Barrage site. The valley is narrow in the portion from Shipkilla

to Pooh and from Thopan to Rampur. In the portion between Pooh to

Thopan and Rampur to Bhakra the valley is comparatively wider. It is

widest in the portion immediately upstream of Bhakra. The bed slope of

river is flat from Shipkilla to Jangi dam site for a distance of about 43 km,

which is of the order of 1 in 175. It becomes steep between Jangi Dam

site and Rampur, the slope being 1 in 87 and is again flatter from

Rampur to Kol Dam site with a slope of 1 in 300. It is the flattest in the

LUHRI HEP

3

Bhakra reservoir area, the portion down stream of the Kol Dam, where

the bed slope is 1 in 500.

2.2 POWER SCENARIO

2.2.1 Sources of energy

India is endowed with a vast hydropower potential. As per the latest

assessment carried out by the CEA, exploitable hydro potential in India

has been estimated at about 84000 MW at 60% load factor, which can

yield an annual power generation of over 440 TWh of electricity and with

additional seasonal energy, the total energy potential is about 600 TWh a

year. Only

14.5% of this potential is under operation and 7.2% of the potential is

under execution. Thus the bulk of the potential amounting to 77.9% is yet

to be developed.

About 73% of India's total installed capacity is thermal-based (Table 3.2).

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. Considering that the capacity of

Indian Railways to carry coal effectively is limited and additional tracks

are required, and the coal is of low quality and costly to transport over

long distances, it appears logical to develop thermal projects in specific

areas, e.g. coal-based projects in Bihar, Orissa, Eastern Uttar Pradesh

and surrounding areas, and gas-based power near the port belts of

Gujarat and Maharashtra, and place total emphasis on hydropower in

States such as Himachal Pradesh, Punjab, Haryana, Western Uttar

Pradesh and far-East India - the Himalayan belt.

LUHRI HEP

4

Table 2.2

Share of Hydropower in India's Installed Capacity

Year

Total installed Capacity (MW)

Hydropower

Capacity (MW)

Share of

Hydropower (%)

1962-63

5801

2936

50.6

1969-70

14102

6135

43.5

1979-80

28448

11384

40.0

1989-90

63636

18308

28.8

1991-92

69070

19189

27.8

1993-94

76718

20366

26.6

In the Northern Region, hydropower is the most suitable source of power

since both thermal/nuclear or other fuel-based source of energy involve

carriage of raw material over long distances making the cost of

development uneconomical. There are no thermal-based power projects

in Himachal Pradesh.

2.2.2 Hydropower potential of Himachal Pradesh

Himachal Pradesh along with the States of Jammu & Kashmir and Punjab

form part of the Great Indus Basin. This basin comprises six major rivers,

viz., Indus, Jhelum, Chenab, Ravi, Beas, and the Satluj, and drains a total

area of 1.16 x 106 km2, out of which 0.17 x 106 km2 lies in India. A total of

about 190 hydropower schemes have been identified in the Great Indus

Basin having a firm hydropower potential of 11993 MW at 60% load

factor.

According to the CEA in its publication "Hydro Electric Power Potential of

India", December 1988, in various States and river basins in the country,

the total potential in Himachal Pradesh is 12480 MW at 60% load factor,

with an installed capacity of 20800 MW.

The Satluj basin in Himachal Pradesh has a hydropower potential of 9444

LUHRI HEP

5

MW, which represents approximately 33% of the likely installed capacity

in Himachal Pradesh. Seven schemes in the Satluj are already in

operation with total installed capacity of 3090 MW. The remaining 6354

MW potential is yet to be developed. Two major projects in the basin

namely 1500 MW Nathpa-Jhakri, a joint enterprise between the Central

Government and the Government of Himachal Pradesh, and the 300 MW

Baspa II Project, a privately-financed development sponsored by the

State Government, has recently been commissioned.

Besides Nathpa-Jhakri and Baspa II, the following projects in the Satluj

basin have been identified and form part of the river unexploited potential.

Kol Dam

800 MW

Rampur

400 MW

Karcham-Wangtoo

1000 MW

Shongtong-Karcham

400 MW

Thopan-Powari

480 MW

Jangi-Thopan

480 MW

Ghanvi-II

10 MW

The proposed Luhri Hydroelectric Project has a capacity of 480 MW and

is located on the Satluj River, upstream of Thopan-Powari Project.

In addition to the Satluj, other rivers which are part of the Great Indus

Basin and pass through the State of Himachal Pradesh, also contribute to

the power potential of the State. The most important are: Beas River,

4586 MW; Ravi River, 2379 MW, Chenab River, 3832 MW.

LUHRI HEP

6

Himachal Pradesh thus has considerable hydropower potential. In the

long run, it is more economical for development than thermal power, as it

utilises perennial natural resource which otherwise goes to waste. For the

prosperity of the state and benefit of the country the hydro-power

development in Himachal Pradesh needs a renewed thrust. The

hydroelectric potential of Himachal Pradesh, however, is not likely to be

consumed in the State, and therefore will be available for meeting the

requirements in other parts of the country, and particularly in the Northern

Region.

2.2.3 Thermal power potential of Himachal Pradesh

Himachal Pradesh being located in the far North end of the country and

considerably away from the coalfields, does not have any prospect of

having thermal projects. The same consideration applies to other northern

states.

2.2.4 Power Scenario in India

The installed capacity in India increased from 1362 MW in 1947 to 64,729

MW in 1990 at the end of the 7th Plan. During that period energy jumped

from 4 to 264 TWh. However, despite that appreciable growth, power

demand has almost throughout outstripped the supply.

At the end of the 7th Plan, the shortfall in energy availability on an " all

India " basis was 6.8%. The corresponding shortfall in peak availability

vis-a-vis demand was about 7.6%. In the Northern Region, the shortage

with regard to peak availability was 19%. In July 1991, the peaking

shortage for the country as a whole increased to 16.7% from 7.6% in

March 1990, while the energy shortage rose to 7.9% from 6.8%.

For the 8th Plan(1992-97), the Central Electricity Authority (CEA) had

LUHRI HEP

7

estimated a need based capacity addition of 48000 MW,which was scaled

down to 30 558 MW taking into account the availability of resources. At

the end of 1997-98 India had an energy shortage of 8.1% and a peaking

shortage of 11.3%. Even with the planned capacity addition of more than

30,000 MW, the shortages in the terminal year of the 8th Plan, i.e. 1997,

would continue to be at the same level. As a matter of fact the situation is

likely to be worse as slippages are anticipated in the planned capacity

addition.

2.2.5 Demand and Supply in Himachal Pradesh State

Himachal Pradesh, being mostly a hilly terrain State and located in the far

North end of the country, considerably away from the coal fields, has little

prospect of having thermal projects. Having considerable hydropower

potential, which is generally found to be more economical for

development than thermal power, power generation in the future for

Himachal Pradesh has to be essentially from hydro-power sources.

As per the 15th Electric Power Survey of India, carried out by the Central

Electricity Authority (CEA), the energy requirement of Himachal Pradesh

for 1990-91 was 1487 GWh. This demand was projected to increase to

2536 GWh in 1994-95. Similarly, the peak load requirement for 1990-91

was 325 MW, which was expected to increase to 541 MW in 1994-95.

Table 2.3 shows the supply of energy and power as well as future

demand during the period 1990-91 to 1994-95 as projected by Central

Electricity Authority (CEA) in the 14th Electric Power Survey of India.

Table 2.3

POWER SUPPLY AND DEMAND FOR HIMACHAL PRADESH

Item

1990-91

1991-92

1992-93

1993-94

1994-95

Installed Capacity

274

274

296

301

301

Peak Availability

340

347

379

458

475

LUHRI HEP

8

Peak Load

325

366

415

477

541

Surplus/Deficit

15 4.6

- 19 - 5.2

- 36 - 8.7

- 19 - 4.0

- 66

- 12.3

Energy Availability

2013

2047

2147

2521

2711

Energy Requirement

1487

1688

1925

2224

2536

Surplus/Deficit

526 35.4

359 21.3

222 11.5

297 13.4

175 6.9

The future demand scenario for the period 1995-2010 as projected by the

CEA in the 15th Electric Survey Report with respect to Himachal Pradesh

is as depicted in Table 2.4.

Table 2.4 Energy and Peak Load Demand for Himachal Pradesh Period 1995 to 2010

Period

Energy Demand (GWh)

Peak

Demand (MW)

1995-96

2879

609

1996-97

3254

683

1997-98

3662

763

1998-99

4103

848

1999-2000

4576

939

2004-05

7378

1457

2009-10

10606

2020

It can be observed that energy requirements are likely to increase during

the period 1991-2010 from 1487 GWh in 1990-91 to 10606 GWh in 2009-

2010, and the peak load demand would do increase from 325 MW to

2020 MW during the same span.

LUHRI HEP

9

2.2.6 Demand and Supply in the Northern Region

The hydropower potential of Himachal Pradesh, is obviously surplus to its

own requirement. However, it will be usefully made available to meet the

power and energy requirements in other parts of the country, and very

particularly, the Northern grid. This is the case of major projects such as

Bhakra and Beas, which supply power to the Northern grid. Another

example is the 540 MW Chamera Project, situated in the north-western

part of the State, which started operating in 1994 and supplies New Delhi

through a 510km long transmission line. For planning purposes it is

therefore necessary to study the energy and power requirements of the

Northern region as a whole, since the region will be the recipient of any

hydropower project likely to be developed in Himachal Pradesh in the

future.

On the basis of the addition of capacity during the 8th Plan period, the

CEA has estimated the requirements of the Northern Region as shown in

Table 2.5.

Table 2.5

Power Demand and Supply for the Northern Region in the Period

1990-95

Item

Unit

1990-91

1991-92

1992-93

1993-94

1994-95

Installed Capacity

MW

19203

20581

22195

24274

26681

LUHRI HEP

10

Peak Availability MW 11408 11291 12777 14008 15271 Peak Load

MW

14908

16259

17721

19240

20814

Surplus/Deficit

MW %

- 3500 - 23.5

- 4338 - 26.7

- 4944 - 27.9

- 5232 - 27.2

- 5543 - 26.6

Energy Availability

GWh

80803

82755

88165

95959

106143

Energy Requirement

GWh

79338

86553

93396

102416

110841

Surplus/Deficit

GWh

%

1465 1.8

- 3798 - 4.4

- 6231 - 6.6

- 6457 - 6.3

- 4698 - 4.2

Table 2.6 lists the future energy and load requirements for the Northern Region.

Table 2.6 Energy and Peak Load Demand for the Northern Region Period 1995-2010

Period

Energy (GWh)

Peak Load

(MW)

1995-96

119887

22466

1996-97

129587

24234

1997-98

139976

26124

1998-99

151086

28143

1999-2000

162954

30295

2005-06

248332

45634

2009-10

318715

58117

From Tables 2.5 and 2.6, it can be seen that the peak demand over a period of 20 years is likely to double from 14908 MW in 1990-91 to as much as 58117 MW in 2009-2010.

2.2.7 Satluj river hydropower potential

The Government of India and the State of Himachal Pradesh have

identified the Satluj river as one of the main sources of hydroelectric

power, and have initiated several hydro-electric projects along the reach

of the river and its tributaries under their jurisdiction. These projects, in

LUHRI HEP

11

varying stages of planning, construction, completion and operation,

include:

- Bhakra-Nangal, 1164 MW, operating

- Kol, 800 MW, concept stage

- Rampur-Behna, 400 MW, concept stage

- Nathpa-Jhakri, 1500 MW, under operation

- Karcham-Wangtoo, 1000 MW, investigation stage

- Shongtong-Karcham, 402 MW, investigation stage

- Thopan-Powari, 480 MW, concept stage

- Jangi-Thopan, 480 MW, concept stage

- Pooh-Spillo 300 MW, concept stage

- Khab-Pooh 300 MW, concept stage

These projects are all run-of-the-river, with the exception of Bhakra-

Nangal. Additional hydro projects, planned and operating have been

identified on tributaries of the Satluj, such as Sanjay Vidyut Pariyojana -

Bhaba (120 MW, operating), Nogli (3 MW, operating), Ghanvi (22.5,

operating), Baspa II (300 MW, Operating) and Baspa I (concept stage).

Some of the potential projects listed here may not be built in near future,

but it is reasonable to assume that the preliminary studies have indicated

these projects to be technically feasible, there will be a strong motivation

to build them as the demand for power grows and limited fuel resources

tend to exhaust.

Further developments, in addition to those listed here, may be seriously

considered at some time on both the Satluj and its tributaries. A program

to develop small hydro projects on streams flowing through villages is

also in place.

2.3 NEED OF THE PROJECT

From the growth of peak demand and anticipated installed generating

LUHRI HEP

12

capacity on the basis of schemes proposed for benefits under

construction/consideration during eighths and ninth five year plan, 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

scheme have to be taken up immediately and implemented to drive timely

benefits.

The most important source of power development in the Northern region

is Hydro resources located in Himachal Pradesh, Uttar Pradesh and

Jammu and Kashmir. Luhri Hydroelectric Project is very attractive

scheme from the view of deriving benefits in the beginning of tenth five-

year plan.

, LUHRI HEP

III - 1

CHAPTER - III PROJECT AREA

3.1 INTRODUCTION

The Government of India and the State of Himachal Pradesh have

identified the Satluj river as one of the main promising future sources of

hydroelectric power. Development of Satluj waters was started in a big

way first by Bhakra-Nangal Project. Government have now initiated

several hydroelectric projects along the reach of the Satluj and its

tributaries. The Luhri Hydroelectric Project is envisaged as a run-of-the-

river development on the Satluj river, in the reach between Luhri and

Chaba villages in Shimla District of Himachal Pradesh just downstream of

confluence of Behna khad with Satluj river nearLuhri.

3.2 LOCATION AND ACCESS

Himachal Pradesh is located in the western portion of the Great

Himalayan Mountain Range of northern India, bounded by the State of

Jammu-Kashmir to the North, Tibet to the East, and the plains of northern

India to the South and West. The Satluj river is one of the major rivers

draining this region. It rises in the Tibetan Plateau, passes via steep

valleys and gorges through the Himalayan Mountains and foothills and

meets the Arabian sea across the plains of Northern India.

The project site area is about 80 km from Shimla, the State capital, and is

an upstream development to the proposed Kol dam Electric Project ( 800

MW) on the Satluj river.

3.3 CLIMATE

The study region is falls between climatic zones I and III of northern India.

Zone I, the Tropical Monsoon climate, extends from the Indian Ocean

, LUHRI HEP

III - 2

north as far as Wangtoo, with its effects modified by elevation and

topography. The tropical monsoon climate involves an

annual rainfall in excess of 1000 mm, occurring mostly in the months of

June to October. The study region, however, experiences lmoderate

rainfall as the mountains between the plains and the study region capture

most of the precipitation.

Climatic Zone III, the Arid Mountain Climate, affecting the Tibetan and

western China Plateau, is characteristically cold and dry in winter, and hot

and dry in summer. This is highly modified by the topography of the study

region. From November to May, the region experiences a generally north-

easterly flow of cold continental air moving out from across the Tibetan

Plateau. The effect of this flow is somewhat modified by the mountains

but it can result in high winds. Winter precipitation occurs as a result of

westerly disturbances. From June to September, the region experiences

the south-westerly monsoon from the Indian Ocean, though, once again

the region's location in the heart of the Himalayas modifies the effect, and

precipitation is small.

3.4 GEOLOGY

The project area lies in Mehbar and Maldi gneisses comprised of kyanite

and psamatic gneisses with bands of schist and quartzite. These are

intruded by basic and acidic rocks. All the rocks are well foliated. The

general trend is N-S with moderate dips toward East. These are

transacted by a number of joints of which the foliation and strike joints are

the most predominant followed in frequency by steeply dipping transverse

joints. The rock formations within the project area going upstream from

the tailrace consist of the Wangtoo, Rampur and Jutogh gneisses and

granites. The Wangtoo rocks are overlaid by the Rampur followed by the

Jutogh, the three series having thrusted contacts.

Rocks are generally covered by glacial deposits, rock debris, alluvial

terraces and fans. The soils of the Satluj valley are relatively poor sandy

, LUHRI HEP

III - 3

loam, and exposed bedrock, rocks and gravel abound. In the valley

bottom there is virtually no soil, but between elevations 1200 and 3500 m,

the soils support some forest cover and are cultivable to a certain extent.

3.5 SEISMICITY

The project area lies in an active seismic region, zone IV of the Seismic

Zoning Map of India. Available data on seismicity within a radius of 150

kms of the project shows that earthquakes having a magnitude greater

than 5 on the Richter scale occur at frequent intervals. Important seismic

events which have taken place in the past 150 years and caused

significant damage include the 1905 Kangra quake (magnitude 8+), the

1908 Kullu quake (magnitude 6.0), the 1945 and 1947 Chamba quakes

(magnitude 6.5 & 6.6), the 1975 Kinnaur quake (magnitude 6.8) and the

1991 Uttarkashi quake (magnitude 6.6).

3.6 SOCIO-ECONOMIC CHARACTERISTICS

The Shimla region has deep roots in Indian mythology, legends and

literature. The Shimla region was formerly a part of the princely state of

Kumarsain / Suni. The State of Himachal Pradesh came into existence in

1960 and Shimla became a district. Contact with the outside world

accelerated when National Highway 22 was built by the Border Roads

Organization, following the 1962 Sino-Indian war. One immediate

consequence of the road construction was that interior of Shimla became

integrated into the cash economy of Himachal Pradesh. The State has

continued to play a role in introducing techniques and policies that have

enhanced production despite the poor soils of the area.

LUHRI HEP

CHAPTER-IV

GEOLOGY

4.1 INTRODUCTION

The Central Electricity Authority (CEA), with a view to fill the gap

between supply and demand in the field of power have embarked on

an exercise to assess balance hydroelectric potential in the country

and rank the schemes thus identified in various parts of the country in

different river basins. As a part of the exercise, 162 schemes with

probable installed capacity of 50,600 MW and located in various river

basins spread over 16 states have to be taken up for preparation of

Pre Feasibility Reports (PFRs) in the first phase. The schemes found

feasible are proposed to be taken up for further development in X and

XI Five Year Plans. The proposed Luhri Hydroelectric Project is one

such scheme identified in Satluj basin in shimla District of Himachal

Pradesh State. Luhri Hydroelectric Project is a run of the river scheme

that envisages the construction of a diversion dam/weir across the river

Satluj near village Luhri (31 21' 40" N: 77 26 25" 'E'; 53 E/7), about

13 km long conductor system and power house on the left bank of

Satluj, 1 Km upstream of village Pandoa (3117'10"N: 7719'10"E, 53

E/7). The proposed power house would have installed capacity of 425

MW.

4.2 REGIONAL GEOLOGY

The area forms a part of the Lesser Himalaya and presents a

diversified relief with high rugged hills of carbonate rocks, deep valleys,

LUHRI HEP

steep escarpments and cliff faces. There is a great variation in altitude ,

from 640 m near Tattapani to 3100 m at Shali peak. The satluj forms

the main drainage system of the area that flows from the NNE to SSW

direction, from north of Jhunajan to Chamba where it takes almost an

east-west trend.. The main tributaries of the river are Nauti, Pandoa

and Sowera Khads, meeting the Sutlej at Chaba, Paildoa and Bagthal,

respectively. A number of small nalas feed these khads giving rise to a

dendritic type of drainage pattern. An oval shaped lake, about 300m

long and 220m broad is located in the east of village Kariali. It has

probably been formed by damming of the northwest flowing nalas by a

landslide mass from the adjoining hills. During the monsoons the lake

gets filled with water which slowly flows underneath and emerges as

springs at Drawl, Graon and then flows in an open channel before

merging with the Sutlej river.

The rocks exposed in the area under reference belong to the Kullu,

Shali and Basantpur Groups. Thelithostratigraphic succession in the

area modified after Sharma and Ahluwalia(1977) is given below:

Basic sills and dykes (intrusives) Shimla Group Basantpur Formation : Grey, dark grey shale, slate,

carbonaceous shale, lenticular

bands of limenstone, quartzite.

-----------------------------------Thrust----------------------------------------------------------------

Bandla Formation Grey siltstone, quartzite and shale.

LUHRI HEP

Pamali Formation Thin bedded limenstone, dolomite,

quartzite towards the top.

Shali Makri Formation Purple, greenish grey slate, splintery,

shale, quartzite and limenstone.

Tattapani Formation Grey and pink massive dolomite and

phylitised shales.

Sorgharwari Formation Pink and grey limestone, Khatpul

Formation Massive dolomite.

Khaira Formation Pink and white quartzite,

Ropri Formation : Not exposed in the area.

-----------------------------------------Thrust---------------------------------------

Khokan Formation Quartzite, quartz chlorite and quartz

biotite schists,

slates phyllites and schists,

garnetiferous schists.

Kullu

Group Garh- Manjrot Streaky mylonitic gneiss, banded and

augen gneisses.

The crystallines and metamorphites of the Kullu Group physically

overlying the Basantpur Formation belonging to Shimla Group along

the thrust (Jutogh Thrust) have been mapped from Naraini Ghati in the

LUHRI HEP

south to Kanda in the north. Between Thach and Naraini Ghati the

Kullu Group rocks at the contract, is represented by dark grey slate,

phyllite and schist followed by coarse grained steaky gneiss dark grey,

green chloride and Biotite-schist coarse grained streaky gneiss

predominates at the contract between Thathal and Kanda.

Except the lower most Formation Ropri, all the other Formations of

Shali Group are developed in the area. Khaira Formation consists of

pink and white quartzite and a small outcrop of this rock, about 50m

long 2.30m wide occurs in the southwest of Kariali. Pink and grey

quartzite of the Khaira Formation is conformably succeeded by grey

blue, massive, tough and compact dolomite. This shows a

characterisitic rugged weathering and encloses impersistent bands of

chert near Darabla, along the road section, about 30 cm thick band of

jet black shale occurs within the dolomite for about 50m along the

strike. The Khatpul dolomite is gradationally overlain by light pink to

light purple, well bedded and laminated lime stone with purple shale

partings. The pink and purple limestone invariably grades into each

other, along, as well as across the strike. Pink limestone, however

remains the dominant and consistent of all the Formations. Lime Stone

breccia, formed by the solution action is met with near Bagh. Calcite

veins are sporadically found in these limestones. A few malachite

stains are encountered in the pink limestone near Karioli. The based

part of the limestone is shaly and cherty. The limestone is traced from

Jhanjan in the northeast to Padian in the southwest over a distance of

about 15 km. with average which of about 500 m. Sorgharwari

Formation passes graddationally into massive dolomite of the

Tattapani Formation. The dolomite contains chert bands ranging in

width from 2-8 cms. The dolomite is grey, grayish blue and pale pink

and contains impersistant grey and black slate partings and phyllitised

LUHRI HEP

shales. In the area the Formation is traced from north of Mungna in

southwest to Jamrog in the northeast over a distance of about 17 kms

with an average width of about 500m. Conforably overlying the

Tattapani Formation is the Makri Formation which constitutes grey,

greenish grey and purple shale and slate. As grey splintery shale, grey

quartzite, grey limestone, cherty splintery shale, grey quartzite, grey

limestone, cherty dolomite and grey quartzite form the components of

this Formation. These are traced from Mungnna in the southwest to

Kanda in the northwest over a distance of about 18 kms with width

varying from 10m to about 1 km. Parnali Formation overlies the Makri

formation. It consists predominantly of grey dolomite, which is highly

cherty and contains lenticular sporadic bands of white and grey

quartzite and thin bedded bluish limestone. This is traced from north of

Sakra in southwest to Rehri in the northeast over a strike length of

about 25 kms with an average width of about 800m. The rocks don't

extend beyond Rehri due to a fault. The youngest Formation of the

Shali Group is the Bandla Formation which comprises grey siltstone

quartzite, shale and sandstone. In the entire area, the rocks are

encountered between LOI and Garrech for a strike length of about 3

kms with an average width of about 500m. A small lens of these rocks

has also been noticed in the northwest of Sai Ser. The absence of this

Formation in the rest of the area is attributed to a fault.

The Shimla Group extends from the Giri to the Satluj and Baghar at the

base of Chunar Mountain Range leaving out the Halog-Chali ridge.

Isolated outliers are seen in the Bharari Khad, Batawara and Kindu

where they directly overlie the Shali Group. The shimla Group again

reappears in the NW part of Himachal, covering Thanoli, Kehluadn the

Ravi over the Shali structural belt and beneath the crystalline thrust

sheet. Its extension beyond the Ravi into the Kashmir Himalaya is

LUHRI HEP

confirmed where it is variously referred as the "Agglomeratic Slate and

Ramban Formation. Beyond the "Syntaxial bend" it passes into the

Hazara Group. In the SE part of the Himachal, Shimla Group rocks

reappear unconformably over the Deioban and beneath the Janusar

thrust sheet of the Nigali Dhar-Korgai synclines of the Blaini-Infra Krol,

Krol-Tal sequence. It continues in that position towards Garhwal

Himalaya before being finally tectoniclly overlapped by the Janusar

thrust sheet. It also crops out in the window zones of Parahat and

Bidhalana in the southern Garhwal Himalaya.

The Shimla Group is divisible into four formations on the basis of certain

characteristic lithological association and order or superposition :

______________________________________________________________________

Formation Members Lithology Thicknes in meters (approx.)

______________________________________________________________________

Upper Conglomerate, arkosic sandstone Proto-quartzite, grey and purple, shale 1600

Sanjauli Lower Greywacke sandstone (medium to coarse-

Grained), greywacke siltstone, shale and

Siltstone alteration, orthoquartzite.

Chhaosa Shale and siltstone alteration greywacke,

siltstone and orthoquartzite. 1300

Kunihar Shale and silt stone alterations with limestone

interbeds (earlier referred to as Kakarhatti 450

limestone)

Basantpur D Thick bedded to platy greyish blue lime-

Stone with interbedded shale (local facies)

LUHRI HEP

C Massive to bedded limestone -

Dolomite (local facies _

B Shale, siltstone with interbeds of lenticular

Limestone; shale is sporadically carbonaceous

Impresistent band of quartzite and dolomite.

A Greyish white quartzite and conglomerate

(sporadic )

Out of the four formations of Shimla Group, the present area contains

only the rocks belonging to Basantpur Formation. The Basantpur

Formation overlies the various formations of the Shali Group and

includes grey, dark grey shales and slates. Highly carbonaceous shale

bearing pyrite, is generally developed near the contract with the Kullu

Group. The carbonaceous rocks are well exposed in places like north

of Garech, west of Thathal, west of Dakolu, South of LOI and North of

Rehri. The rocks, at place, contain thin lenticular bands of platy

limestone. A number of such lenticular bands of limestone have

developed over a wide area around Naldehra. Small outcrops of grey

platy limestone having a resemblance with that of the Basantpur

Formation occur within the rocks of the Shali Group in the south of

Naklog Ghati, southeast of Senu (in Makri Formation) and west of LOI

(in Paruali Formation). The Contact between the Shali Group and the

Basantpur Formation is a tectonic one. The rocks have been traced

from Chaba to Baldiha and from Dalog Pass to Kanda.

Several sills and dykes of doleritic and dioritic composition cut across

the various Formations of the Shali Group along the weak planes.

Such intrusives of various shapes and sizes have been recorded in the

LUHRI HEP

Sorgharwari Formation around Kariali, east of Kothi, southeast of

Bathora; in the Tattapani Formation in the north Markalu;in Parnali

Formation in the east of Uparia Kayalu and in the Bandla Formation

north of Khaibal. The intrusives do not show any contact effects with

the wall rock, probably indicating the low temperature conditions of the

intrusion.

The Shimla Group is generally free from volcanic element. However,

locally dolerite-diabase dykes are seen intruding into the Shimla Group

and are particularly seen in the Basantpur Formation. Such dykes are

seen in Basantpur - Seoni area.

The Kullu Group fully frames the Larji-Rampur Window Zone, and is in

turn, partly framed by the Salkhala on the western side and by the

Vaikrita on the eastern side. In the southeastern part it lies on the

subthrust side of the Jutogh Thrust Sheet. Further west and northwest

it rests over the Shalli Structural Belt along Suketi Thrust as a long,

linear and narrow nappe. Beyond the Ravi in the Jammu-Kashmir the

thrust links up with the Punjab Thrust. The Kullu Group is one of the

three principal crystalline nappes of Himachal Pradesh.

The Kullu Group comprises the following sequence of formations.

Khokaan Formation Quartzite, quartz chlorite and quartz biotite schists, slates

phyllites and schists, garnetiferous schists.

Garh - Manjrot Streaky mylonitic gneiss, banded and augen geniesses.

Formation

LUHRI HEP

Khamarada Formation Carbonaceous to graphitic schists and phyllite locally

garnetiferous; lenticular greyish blue and cream coloured

platy limestone and calc-schists.

--------------------------------------------Thrust------------------------------------------------------

The Kullu Group constitutes the southern frontal crystalline thrust sheet

tectonically transgressing over the Lesser Himalayan Tectogen. One

characteristic features of the Kullu Thrust sheet is the development of

a highly sheared mylonite gneiss (Manjrot - Garh Gneiss) tectonically

intermixed with the carbonaceous phyllite and limestone along the sole

of the t hrust sheet particularly in the sector from Baragaon in SE to the

Rani in NW and also around the Larji-Rampur Window Zone. This

thrust represents a major and the most pronounced tectonic

discontinuity in the Himachal Pradesh and can bde equivalent to the

Main Central Thrust of the Himalaya (Srikantia, 1988).

Garh- Majrot Formation connsist of quartzose, banded and streak

gneisses, pale greyish green in colour, showing alternate beds of

schist and quartzite and even carbonaceous phyllite. The gneiss is

highly streak and strongly foliated and mylontised augens of feldspar.

Coarse grained of blue quartz stand out prominently. In Baragaon in

the Satluj Valley the Garh- Manjrot gneiss appears prominent along the

Kullu Thrust Sheet. In Himachal Pradesh the Garh - Manjrot Gneiss is

fairly persistent along the strike and occupied a definite tectono-

stratigraphy position.

Khokhan Formation comprise mainly of quartzite, quartz schist, quartz

chlorite and quartz biotite schist, slates, phyllites and garnetiferous

schists. Locally amphibolites appear associated with the

LUHRI HEP

metasediments. The Formations is tectonically succeeded by the

Jutogh Thrust sheet on Satluj valley.

4.3 STRUCTURE AND TECTONICS

The Kullu Group consisting of carbonaceous schist, chlorite schist and

augen gneiss physically overlies the rocks of the Basantpur Formation

along a thrust (Jutogh thrust). The contact between the Shali Group

and the Basantpur Formation is tectonic and shows evidence of

movement. The regional strike of the rocks formations is NW -SE with

dips varying from 200 to 700 on either side. The area reveals a

regional anticlinal structure with its axis running in NW -SE direction.

A number of open and overturned type of folds developed in the Shali,

have increased the outcrop width of the deposit on the eastern limb.

Cross folding in the area has resulted in the formation of a

complicated outcrop pattern. Dolomite of Parnali Formation is folded

into a syncline with a N60E-S60E trending axis. This may be

complementary to the main anticline. In the northeastern part of the

area the contact between the Basantpur Formation and Shali Group is

faulted and the along this fault the Parnali and the Bandla Formation

have been eliminated. In the Nauti Khad area (southwestern part) also

the Basantpur Formation has been brought to rest over the Parnali

dolomite along a fault. A few oblique faults are also noticed in the area.

4.4 SEISMOTECTONICS AND SEISMICITY Seismotectonically, the area is located on eastern margin of Shinmla

Tectonic Block of Narula (1991). It is bound by Sundernagar Fault in

west and Kaurik Fault in east. The project area is located in Main

Himalayan Belt where the tectonic packages are Tethyan and Lesser

LUHRI HEP

Himalayan cover sequences affected by Himalayan Orogeny, low and

high grade complexes tectonically reworked during Himalayan

Orogeny and pre to syntectonic granitods and basic volcanics. The

Foothill Belt constitutes foredeep sediments affected by the terminal

phase of the Himalayan Orogeny (Narula et al.). The northernmost

tectonic element is the dextral Karakoram Fault (KF) which is

subparallel to Indus Suture Zone (ISZ) occurring to the south. Within

the Main Himalayan Belt, the high grade complex is bound in south by

Main Central Thrust (MCT) which is considered most conspicuous

structural element of the Himalayas. Further South, within lesser

Himalayas, the other important tectonic element is Vaikrita Thrust (VT).

The Lesser Himalayan Belt is separated from the Frontal Belt by Main

Boundary Thrust (MBT). The sourthern limit of Frontal Belt is marked

by Main Frontal thrust (MFT). A part from the tectonic planes sub-

parallel to Himalayan trend, a number of transverse features have

been observed. These include Sunder Nagar Fault, Kaurik Fault and

Raura Fault. In the Higher Himalayas, Kaurik Fault Zone is considered

to have triggered the Kinnaur Earthquake of 19th January,1975. The

present area also have Salkhala and Jutogh Thrust which are present

near Karchhaim. Neotectonic activity has been observed along

Karakoram Fault, ISZ, MBT, MFT and Kaurik Fault. Seismically, this

area has subdued seismicity but the areas immediately NE of it, the

clustering of seismic events is observed in the Zone known as Kinnaur

Seismic Zone having N-S alignment. It is traversed by a number of half

graben faults defining Kaurik Fault system. The seismic events in

general in this Zone are shallow focus (0-40 km) but a few events with

intermediate and deeper depths have been observed. To the west of

the area lies Kangra Seismic Block, which is considered very active

seismic zone and has experienced 20 earthquakes with magnitude

more than 5. As per Seismic Zoning map of India (1S:1893-1984), the

LUHRI HEP

area lies in seismic Zone-IV and a number of regional thrusts and

faults are located in the vicinity of the project. Therefore, it is

suggested that appropriate seismic coefficient may be incorporated in

the design of the appurtenant structures of the project.

4.5 GEOTECHNICAL APPRAISAL The proposed Luhri Hydroelectric Project a run of river scheme

proposed in Satluj Basin in Shimla and Kullu districts of Himachal

Pradesh envisages construction of a diversion dam across the river

Satluj near Luhri, a water conductor system comprising 13 km long

head race tunnel to conduct water to proposed powerhouse of the

river Satluj near Pandoa village. The area exposes the rocks belonging

to different formations of Shali, Shimla and Kullu Groups of Proterozoic

age. The contacts between the rocks of different groups are either

faulted or thrusted.

At the site of proposed diversion the river Satluj flows towards NW

through a narrow valley. The area exposes quartzite, banded streaky

gneisses with interbands of schist and quartzite and carbonaceous

phyllite belonging to Garh Formation of Kullu Group. The gneiss is

highly streaky, strongly foliated and mylotinised. Augens of felspars

and coarse grains of the quartz can be observed. The foliation trends

vary from NE-SW to NW-SE. It is suggested that the final location and

type of diversion structure be decided after assessing the thickn ess of

overburden in the river bed and on the abutment and availability of site

for locating proper intake structure for headrace tunnel.

The proposed 13 km long headrace tunnel is aligned in NE-SW

direction on the left bank of the river Satluj. It is likely to encounter the

LUHRI HEP

rocks belonging to Khokan and Garh Formations of Kullu Group and

Sorgharwari, Tattapani, Khaira and Makri Formations of Shali Group

and those of Basantpur Formation of Shimla Group that includes

Shale, Slate, carbonaceous shale with limestone and quartzites. Both

the contacts of this formation are thrusted. The rocks of Shali Group

comprise sedimentary sequence including quartzite,

limestone/dolomites and shales. These rocks are expected to provide

good to fair tunnelling media in general. The HRT is expected to cross

two thrusts along its route. Difficult tunnelling conditions could be

expected in Zones around these thrusts. The conditions may become

poorer if these zones are charged with water. It is suggested that

adequate rock cover over the structure be ensured where it crosses

the surface drainages. It is also suggested that excessive cover over

the structure may also be avoided since hot springs present in this

area and adjacent areas indicate presence of geothermal field that

could result in relatively high temperatures during tunnelling.

The proposed powerhouse with 425 MW installed capacity is

envisaged on the left bank of Satluj near the village Pandoa. The area

exposes pink and grey limestone belonging to Sorgharwari Formation

of Shali Group. It is suggested that the site selected for the structure

may have sound bedrock at reasonable depth and adequate space

free from natural hazards like landslides and enough working space

and suitable locations for other appurtenant structures. The site is

located in Zone IV in Shimla Block of Narula (1991) as per Map of

India Showing Seismic Zones. It is suggested suitable seismic

coefficient be incorporated in the designs of appurtenant structures of

the project.

LUHRI HEP

The geotechnical appraisal is based on regional geological set up and

is without field visit to the project site.

REFERENCES:- Narula, P.L., (1991), Seismotectonic Evaluation of NW Himalayas,

Unpubl. Progr. Rep. Geol.. Surv. Ind..

Narula P.L.Acharayya, S.K. and Banarjee, J(2000). Seismotectonic

Atlas of India and is environs. Pub. Geol. Surv. Ind.

Sharma O.P. and Ahluwalia, A.D. (1977) Report on limestone

investigation, Shimla district, Himachal Pradesh. Unpubl. Progr. Rep.

Geol. Surv. Ind. (1978-77)

Sirkantia, S.V. and Bhargava, O.N. (1988) Geology of Himachal

Pradesh Geol. Soc. Ind. Bangalore, P.406.

LUHRI HEP

V-- 1

CHAPTER-V

HYDROLOGY

5.1 INTRODUCTON

Satluj river is one of the principal river of Himachal Pradesh and it divides

the District Kinnaur into two parts. In its passage through Distt. Kinnaur,

the Satluj river crosses three more or less parallel mountain ranges viz. the

Zaskar Mountain, the Great Himalayas and the Dhauladhar Ranges.

Between three mountain ranges lie the subsidiary valleys of varying

dimensions from the narrow glens and ravines of Tidong and Kirang

streams to the sizeable valleys of Spiti & Baspa river. The significant

tributaries streams and rivers that flow into the Satluj river from south or

along its left bank are successively the Tidong, Hogis, Gyamthing, Baspa,

Duling, Sholding, Manglad etc. Likewise those entering from the north or its

right bank are the Spiti River, Ropa, Kirang, Kashang, Pangi, Choling,

Bhaba, Sorang, Kut and Ganwi Khud. In between there are many seasonal

streams that meet the Satluj river and its tributaries. At Khab it receives the

Spiti river where the bed of the stream is still about 2590 meter above the

mean sea level.

Satluj river rises from Rakas Tal fed by Mansarover lake in Nari Khorsam

province of Tibet and after flowing in West direction for a distance of about

300 Km., it enters India near Shipkilla in District Kinnaur. The Satluj

descends from about 2590 meter at Khab to 936 meters at Rampur

Town, in Distt. Shimla, the main supply station to Distt. Kinnaur. The Satluj

flows in this whole reach between narrow cliffs and therefore there is no

open ground worth describing all along its banks, thus excluding the

possibility of making any storage Dam. The water of the river is more or

less discoloured. Cultivated fields in terraces are generally at considerable

heights from its bank and are thus immune from the turbidity of the

water, which is largest in summer months. Within the limits of the District

LUHRI HEP

V-- 2

Kinnaur the river is not navigable owing to the rapidity of flow and presence

of boulders. After it leaves the boundary of the District Kinnaur near village

Chaura it enters Shimla District.

5.2 CATCHMENT CHARACTERSTICS

The geographical limits of the Satluj basin upto Bhakra Dam lie between

latitude 3015' N to 3125' and longitude 7715' to 7730' It covers its area

in Nari Khorsam province of Tibet (China) and in Himachal Pradesh State

of India. The catchment area at upstream of Rampur is about 50880 Sq.,

Km out of which about 36900 Sq.Km falls in Tibet and 13980 Sq. Km in

India. Catchment area upto Luhri dam site is 52403 Sq.Km.

The basin represents some remarkable physical features. Below it

stretches the loftiest mountain ranges of world radiating from the Pamir

knof. The most southerly of these is the Himalayan Range, which is loftiest

and longest range in the world.

The Himalayas that run first South-East-wards from the Pamir knof and

later in an easterly direction constitute a massive mountain wall extending

over 2500 Km with varying width of 250 to 300 Km.

Topographical and climatically the catchment have been divided into four

categories as below: -

i) Tibetan Plateau

River Satluj rises in Tibetan plateau in the region of the Mansarover Lake

situated at an elevation of 4510 Km above mean sea level. The river

passes through the Tibetan province of Nari Khorsam. The best-known

portion of Nari khorsam and the plateau situated between Zaksar and

LUHRI HEP

V-- 3

Ladakh ranges. This plateau has been formed by the successive deposits

of boulders, gravel, clay and mud in the trough between two ranges. The

deposits lie in parallel and nearly horizontal beds. River Satluj has been

able to cut a channel about 915m deep through the plateau with the water

received from glaciers. The vertical banks stand un-eroded, as there is no

local rainfall. River Satluj in Nari Khorsam region is joined by several

tributaries. The beds of which lie about 305m or more below surface of the

plain and their over changing cliffs similar to those of Satluj have been

spared from destruction by rain. The flat portion of the plateau now

remains standing between profound gorges. There is absolutely no

vegetation in this region when the snowmelts deep channels are formed on

the surface. The river Satluj enters India near Shipkilla after traversing a

length of about 320 Kms in the Tibetan province of Nari khorsam.

ii) Spiti Valley Spiti river is the biggest tributary of the river Satluj and joins river Satluj at

Khab, 14km upstream of Pooh. The characteristics of this catchment area

drained by river Spiti is between 3048 m and 4570m. In this area there is

absolutely no vegetation. The melting snow forms deep flow channels.

iii) Namgia to (Wangtu) This catchment is bounded by moderately high hills 1900m to 3048m and

has little rainfall but heavy snow. The snow line in this region is at 3048m.

The flows in the river are mainly due to snow melting which follow more or

less a regular pattern. Due to the absence of rain, arid\condition prevails

and good forests seen below Reckong Peo do not exist in higher altitude.

The well-formed pine forests near Karcham Wangtu give way to Chilgoza

plantations at the higher elevation. The area has steep slopes with little

earth cover and experiences very little rain.

LUHRI HEP

V-- 4

When snow falls, water enters into the rock crevices where its freezing

during winter cracks and crushes the rocks. The subsequent loads of snow

accelerate this phenomenon. When the snow melts, the disintegrated

debris slide with the water into the river. This cycle repeats year after year.

IV ) Wangtu to Suni The annual rainfall of the catchment is about 1000mm.The area is forested

with scattered to dense patches of trees. There is agricultural development

in several locations mainly along the river and on flatter slopes.

V) Suni to Kol Dam and up to Bhakra Dam This area is in the lower elevations of the Shivaliks range with rise to about

elevation 2100 m. The average slope of the river between Rampur to

Bhakra is about 1 in 300 .The rainfall is heavy and silt loads are high.

Forest cover is sparse and vegetation has been denuded by over- grazing.

5.3 THE RIVER PROFILE

River Satluj rises near Rakas-Tal lake which is fed by lake Mansarover at

about 4570m above mean sea level between Rakas-Tal and Shipkilla, near

the Indian border, the Satluj river takes a North-Westerly course for a length

of about 320 Km in the Tibetan province of Nari-Khorsam. The Satluj is

joined by several tributaries in Nari-khorsam such as Changchu, Drama

Yankti, Chonak, Manglan, Transuo, Summa, and Trap etc. Immediately

after entering the Indian territory near Shipkilla the river takes a south-

westerly direction on its way to Bhakra gorge about 320 Km away after

crossing which it emerges onto the plains of the Punjab. The Satluj crosses

the Great Himalayas at a point where the range bifurcates. At Rampur, it

crosses the Dahuladhar range then traverses through a series of

successive Shivalik ranges and the Naina Devi range, where the Bhakra

LUHRI HEP

V-- 5

dam is situated, is the last of the series. Between Suni and Dehar, the river

takes a somewhat north-westerly direction. After Dehar, the river turns in a

south- westerly direction to reach the foot of Naina Devi range. The Naina

Devi range deflects the river again in a north-westerly direction when it

flows parallel to the range for about 32km before cutting through it at

Bhakra gorge.

The principal tributaries of the Satluj below Shipkilla are the Spiti, Kashang,

Baspa, Bhaba, Nogli, Kurpan, Nauti, Sholding, Sorang, Bharari, Ali and

Ghambar khad.

Numerous glaciers large and small drain into the Satluj at various points on

its course. East of Mansarover and feeding its principal source are the

glaciers of the Ganglug Gaungni, the southern glaciers of the Gauglung

Gangni, glaciers of Kailash flow into the Satluj through the lake of Rakas

Tal, The Northern glaciers of peak Kamer also contribute to the streams.

The glaciers of peak Riwa phargul which stands in the Satluj catchment

also flow into it. There are many Himalayan glaciers draining into its

tributaries. The Baspa and many more from the direction of the Bara-Lacha

pass from the watersheds of the Chenab and Beas.

The fall of Satluj from its source to the plains of India is very uniform. The

height of the bed is about 4570m near Rakas-Tal, 2530m near Shipkilla,

915m at Rampur, 416 m at Bilaspur and 350m at the Bhakra Dam site.

The total catchment area of the Satluj above the Bhakra dam site is about

56875 Sq.km (21960 Sq.miles) and above the Luhri diversion site is about

52403 Sq.km (19235 Sq.miles). The river Satluj drains an area of about

50880 Sq.km (196745 Sq.miles) at Rampur discharge site.

A gross fall of 2180m is available in the river bed from Shipkilla to Bhakra in

LUHRI HEP

V-- 6

an length of about 320 Km. The valley is narrow in the portion from

Shipkilla to Pooh and from Thopan to Rampur. In the portion between Pooh

to Thopan and Rampur to Bhakra the valley is comparatively wider. It is

widest in the portion immediately upstream of Bhakra.

The bed slope of river is flat from Shipkilla to Jangi dam site for a distance

of about 43 km, which is of the order of 1 in 175. It becomes steep

between Jangi Dam site and Rampur, the slope being 1 in 87 and is again

flatter from Rampur to Kol Dam site with a slope of 1 in 300. It is the flattest

in the Bhakra reservoir area, the portion down stream of the Kol Dam,

where the bed slope is 1 in 500.

5.4 HYDROMETEOROLOGICAL ASPECTS 5.4.1 General

The climatic conditions of the Satluj River basin are strongly influenced by

orthographic effects. Elevation 1525 m is the approximate boundary

between areas receiving the majority of precipitation in the form of rain and

those receiving mostly snow.

The catchment in Tibet receives practically no rainfall and precipitation is

mostly in the form of snow. No meteorological data for this catchment is

available for the present study. No precipitation observation is available for

Spiti Valley for this study. Observations at six precipitation station i.e.

Purbani, Kalpa, Sangla, Nichar and Rampur are being carried out in the

catchment in Distt. Kinnaur.

These observations, rainfall since long and snowfall introduced only

recently, are being conducted in a conventional manner. There is no self-

recording rain gauge/snow gauge station in the catchment up to Shongtong

LUHRI HEP

V-- 7

Barrage. There are in all twenty rain gauge stations in the catchment up

to Bhakra Dam site at which long term records are available.

5.4.2 Precipitation

The project catchment receives precipitation due to the South-West

monsoon as well as due to the western disturbances that pass over the

north-west part of the country during winter. On the basis of information

gathered from the different sources, it may be said that South-West

monsoon generally lasts from June to September but may occasionally

extend up to early October. Precipitation during this period which falls as

rain is generally not heavy but at times may contribute significantly towards

flood runoff. The winter precipitation falls either as rain or snow depending

upon altitude and other meteorological conditions and may be very heavy

on occasions but may not contribute directly to river discharge significantly

and mostly goes to feed the snow glacier bound areas of the catchment.

The number and distribution of rain/snow gauges is too small and

scattered to give any quantitative information regarding rain or snow that

occur over different parts of the year over the catchment.

5.4.3 Record of Precipitation

There are at present twenty rain gauge stations in the catchment of Satluj

River upstream of Bhakra, at which long term records are available. The

relevant details of these stations are given in the following table.

LUHRI HEP

V-- 8

TABLE

DETAILS OF RAINGAUGE STATIONS

Sr.No. Name of Station Year of Altitude Average Rainfall

Commencement (m) (mm)

1 Bilaspur (Sadar) 1954 580.25 1103.80

2 Bilaspur (Obs) 1957 587.03 1226

3 Ghumarwin 1958 637 1215.40

4 Arki 1951 1219.20 1228.00