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7/30/2019 Guidelines Invetigation Major Irrigation Projects 1975
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GOVERNMENT OF INDIA
CENTRAL WATER COMMISSION
GUI DE L I NE S F OR
INVESTIGA TIONS OFM AJ OR I RRI GATI ON AND
HYDRO-ELECTRIC PROJ ECTS
NEW DELHI AUGUST 1975
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MAJOR IRRIGATION AND HYDRO-ELECTRICPROJECTS
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Water resources development provides the basic infrastruc-ture for the gro'wth of our national economy, and consequently large
investments are being made on projects for the purpose in our
country. Once they are completed, such projects cannot be alteredafter discovery of any shortcomings. Failure of large water retain-
ing structures will lead to heavy loss of life, besides enormous
. monetary losses. There is' need, therefore, for comprehensive in-vestigations and planning of new projects.
Unlike buildings, roads or industrial projeets,water re-
sources projects are more complex and their planning involvesmulti-disciplinary activities. Economic demands, agronomic, geolo-
gic, meteorologic, topographic, hydrologic, engineeing and many
other factors all have impact on their preparation and each requires
careful study. It is true that for such highly complex projects, itis not unusual, that, unforeseen factors like unfavourable geological
conditions are actually revealed during construction of heavy struc-
tures. It is however possible by means of adequate investigationsto keep such uncertainties to the minimum.
The Planning Commission have from time to time issued
instructions on the formulation of new projects and laid down
questionnaires which have to accompany new project reports. Inorder to supplement these, the erstwhile Central Water and PowerCommission compiled, in February 1972, guidelines laying down the
minimum investigations of major irrigation and hydroelectric projects
.and sent these to the State Governments. An addendum detailing theinvestigations for irrigation and power channels and allied canal
structures was sent in December 1972.
Due to increases in costs of labour, construction materialsand equipment, the costs of projects are increasing. It is needless
to emphasise that the new projects have to be planned carefully toevolve the most economic means of affording the planned benefits
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and this will be feasible only if comprehensive investigations on thelines indicated in this booklet are carried out.
Environmental considerations are now recelvlng increasing
attention in the planning of projects and guidelines to cover these
aspects were circulated in July 1975.
In view of several requests from project engineers for
copies of these guidelInes, the various communications of theCommission in this regard have been compiled together and printed.
The Central Water Commission would appreciate any sugges-
tions for improvement of this publication.
New Delhi,the 13th August, 1975.
Sd/ -(Y. K. MURTHY)
Chairman
Central \Vater Commission
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Introduction
Topographical Surveys
Geological and Foundati.on Investigations
Meteorological and Hydrological Studies
Pre-Irrigation_ Soil Survey and. Drainage Soil Survey
Special Surveys for Hydro- Electric Project
Construction Material Investigations
Communications
Construction Plap...ning
Environmental Considerations
Appendix I
Appendix II
Appendix III
Appendix IV
Appendix V
Appendix VI
APPENDICES
Map of India showing the principal lithological groups.
Seismic zones of India.
Seismic coefficient for some important towns.
Composition of Inter-disciplinary official body.
. Map of India showing the annual normal rainfall.
Soil Mapof India.
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GUIDELINES FOR INVESTIGATiONS OF MAJORIRRIGATION AND HYDRO-ELECTRIC PROJECTS
. In order to ensure preparation of sound and economical
projects. it is necessary' to have thorough and systematic investiga-tions. The investigations should include the study of various alter-
natives regarding the layout of the scheme as a whole and also de-
tails -of alternatives considered for the type and location of variousfeatures. of the project. The fi~al alternative recommended should
be fully justified recording the reasons f9r its choice as againstthe others. The minimum surveys and investigations necessary for
the purpose are of the following nine types:
8. Collection of relevant data for drawing out programme
of construction including coffer dam construction.
9. Hydraulic model studies for setting the important
features of the project.
General and broad requirements with regard to each of theabove type of investigations' are set-forth hereunder.
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1.1 Surveys for preparation of plans should be carried out of
the area covering the dam site, the reservoir area and other project
features. Property surveys should be done for the reservoir area.Adequate number of G.T. S. Bench marks should be got establishedby the Survey of India.
1.2 Survey plans of the project will be prepared and exhibited
to cater. to requirements as indicated below:
i) The dam site topographical survey plans sl'!5mldcover an
area sufficient to accommodate all possible arrangem~nts of the pro-jects (dam, spillway, outlet works, diversion works etc.). For a
large structure, a scale of 1/1000 with contours at intervals of 2m.
would be adequate. Unless otherwise necessary, the plan will coveran area at least upto about 200 m. upstream and 400 m. downstreainof the dam site and extend well beyond the abutments.
ii) The reservoir submergence plans may be prepared to
scale of 1/ 15000 with contours at intervale v(2 m to 3 m depending
upon the size of the reservoir. Area capacity curves and tables
will be prepared to an elevation high enough to allow for the antici-
pated maximum reservoir level.
iii) The command area survey plans may be to a scale of
1/15000 with contour intervals of 0.5 m.
iv) For a barrage structure, detailed survey maps will
cover the area under the barrage and appurtenant works (guide banks),
head regulators, road and rail approaches, site for colony etc. The'.plan may be to a scale of 1/4000 with levels in a 30 m. grid.
(v) River surveys in a length of about 10 km. upstream
and 10 km. downstream of the diversion structure will be carriedout. On the basis of this survey, an L-Section 'of the river will be
prepared. Cross-sections will be taken 30C m apart, extending
sufficiently above the H. F. L.
vi) Along the canals alignment, L-Secti-on should be pre-
pared with levels at 50 m. intervals and cross-section 100 m apart
extending to 100 m on either side of the centre lin~$ of the canals.
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The longitudinal sections should show the soils that will be met within the canals excavation.
vii) Surveys connected with cross-drainage works shouldinclude L-Section and cross-sections of the drains, along with de-
tails of catchment areas, high flood discharges, observed H.F. L.
along with canal data at the point of crossing.
viii) For the location of power station, the survey plan
should cover an area sufficient to include alternative station layoutsand should give contours at intervals of 5 m. Low Water level,
maximum. observed flood level, rock outcrops, sand shoals, etc.
where the plant is to be, on the bank of the river, will be indicated
therein.
ix) L-Sections covering power channels, penstocks and
tailrace channels should be prepared. The .L-Section should givelevels at 50 m. inte1..~valsand should show log of boroholes at
points recommended by the geologist of Geological Survey of India.
Cross-Sections should also be taken at 100 m. intervals extendingsufficiently on both sides.
x) For tunnels, longitudinal sections along tunnel alignment
and contour plan with 50 m intervals covering about 100 m on either
side of the alignment and also upto contours corresponding to tunnel
grade, if applicable, indicating location of adits.
Xi.) For surge tank contour plan of surge tank area at 5 m
contour intervals.
xii) For underground power house, .contour plan at 1 in
4000 showing contour intervals at 15 m covering location of accesstunnels, tailrace tunnel, and switchyard.
2..1 A resume should be prepared for the regional geology.
Geological sections to show k"TIownand interpreted sub-surfaceconditions should be prepared. A geological map appended' to this
note gives the general pattern of geological strata met with in
various places of the country (Appendix 1).
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2.2 Seismic conditions of the region should be investigated with
reference to the geological map of the vicinity. For the purpose of
determining the seismic co-efficients the country is divided into five
zones as given in the map (Appendix II).
2.2.1 Unless otherwise stated, horizontal seismic coefficient for
static design in different zones shall be taken as follows (see 2.2.3).
V
IV
III
II
I
Horizontal Seismic coefficient h
0. 08
0. 05
0. 04
0. 02
0. 01
For detailed "design practice, please refer to 1.S. Code
No. 4362 of 1967 and its subsequent amendments BDC (39) (1968)
which is under print.
VALUES OF "B" FOR DIFFERENT SOIL FOUNDATION
SYSTEM
S1. rType of soil I Bearirig
No. 'mainly consti- IPiles
'tuting the I resting
'foundation Ion soil, Type I
Ior RaftIfound-, ation
1 '2 3
Value of "B" forI Friction I Isolated
I Piles, I Footings
I Combined I without
I or Isola- I the Beams
I ted ReC I or Unrein-
I footings I. forcedI with the I strip
I beams I foundations 1
4 5
Well
I foundation
i) Type I Rock
or Hard Soils
ii) Type II Me-dium Soils
iii) Type III Soft
Soils
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2. 2.2 The seismic coefficients according to 2"2. 1 for some impor-tant towns and cities are given in Appendix III.
2.2.3 Buildings provided for accommodating essential services
which will be of post earthquake importance, such as hospitals,
emergency relief stores, foodgrain storage structures, waterworks,
water towers and power stations shall be designed for one and. halftimes the seismic coefficient given in 2.2. 1 or one and a half times
the F-values specified in Appendix of Revised 1.S. 1. Code of Prac-
tice for Earthquake Resistance Construction of Building.
2.2.4 The vertical seismic coefficient where applicable may be
taken as half of the horizontal seismic coefficient as indicated in2.2. 1.
The design seismic coefficient should ~egot confirmed fromthe standing committee set up for the purpose by the Ministry of Irri-
gation and Power and composition of the Committee is enclosed in
Appendix IV.
Evaluation of seismic status of faults and thrusts and collec-
tion and maintenance of seismological data both in pre-constructionas well as post construction stages of river valley projects are of
vital importance because of safety reasons. Recommendations givenin 1.S.1. Code No. 4967-1968 for seismic instrumentation for River
Valley Projects may be used for investigation of seismicity of site
for any project besides river valley projects, if the situation and
the magnitude of the project justifies so.
2.4 Geological investigations should ,be carried out for determin-
ing the water tightness of the proposed reservoir, presence or other-
wise of solution channels. sink holes, etc. and the existing and poten-
tial slide areas. The survey should also include an assessment of
valuable mineral deposits in the reservoir and existing and potential
slide areas.
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i) Boreholes at a minimum spacing of 150 m all along the
dam alignment should be drilled to a depth equal to the height of the
dam at the location of the hole or 5ill below bedrock whichever ismore. The method of drilling adopted should be specified. Bore-hole logs for soil strata must be in accordance with 1.S.1. Unified
classification system.
ii) In situ permeability tests in all the boreholes should
be carried out at various depths of hole.
iii) For cohesive materials, at least one undisturbed
sample for each soil stratum met with shall be tested for in-situ
density and natural moisture content as well as for shear para-
meters in triaxial shear with pore pressure measurements under
saturated condition. Degree of compaction of the foundation ma-terial in terms of Proctor density for the material in each stratum
will be determined.
iv) Where the foundation. material is cohesionless, the
relative density of the material will be determined at various depths,
extending upto a depth equal to the height of the dam or to rock
whichever is higher.
Masonry I Concrete Dams
) i) Exploratory holes andlor drifts should cover the entirefoundation and abutment area of the dam including energy dissipation
structure. The location, spacing and depth of holes shall be de-cided in consultation with an engineering geologist of the Geological
Survey of India.
ii) Description and logs of exploration should include
ground elevation at the hole, location coordinates and sufficiently
detailed remarks regarding the nature and type of rocks, geologicalstructure, water loss etc. for a clear interpretation of the founda-
tion conditions.
iii) Contours of bed rock and geological structure of found-
ation strata should be presented.
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iv) Location and thickness of weathered, altered or other-
wise softened zones and their characteristics and the structural
weaknesses and discontinuities shall be investigated.
v) Tests for significant engineering properties of founda-
tion rock such as density, absorption, permeability, shear compres-
sive strength and strain characteristic (including the effect of mois-ture content) should be done and data presented. Where the type
andt or structure of rock is such that its competency to ensure the
stability of the dam"against a sliding failure is in doubt, necessary
in-situ shear tests should be done and data presented.
Barrages tWeirs
i) Along the proposed alignment of the barrage, explora-
tory holes spaced 150 m apart should "be put to determine soil
profile upto a depth of 30 m below average bed level on permeable
strata. Where sheet rock is met earlier, the depth of drill holesmay be taken 3 m in rock. .
ii) Samples of soil obtained from bore holes should be
tested for properties as set forth under items 6.4.2.
Water Conductor System
i) The L-Section of the water conductor system from intake
structure to tail-race should be given. In power channel portion,
trial pits to adequate depth be put in at suitable intervals so as to
indicate all changes of strata.
ii) For tunnel, a geological section of the tunnel alignment
and surge shaft and drill holes adequate to establish cover of rock
and important geological features should be given.
i) 2 to 4 drill hole details for the power station area may
be given. The number, location, spacing and depth shall be decidedin consultation with an engineering Geologist of the" Geological Surveyof India.
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include switchyard and alternative plant lay-outs and should give
contours at intervals of 5 m. Low water level maximum observed
flood level, rock out crops, sand shoals etc. at the power house
site will be indicated therein.
iii) Indications of slides and their locations and the possi-
bility of rockfalls in the hill slopes should be explored.
v) For underground power house, a geological sections of
power house, pressure tunnel, access tunnels and switchyard and
sufficient drill holes /drifts to establish the geological features of thesame.
2.5. 6 Irrigat~on and Power Channels and Canal Structures
(a) Plans to be attached
1. Index Plan showing the entire canal system and the whole
scheme.
2. The command area survey plan to a scale of 1/15'000 with
contour intervals of 0.5 m.
3. L-Section:- Along the canal alignments, L-Sections should
be prepared with levels at 50 m. intervals indicating thefollowing details:
vi) Type of 'Canal, nature of soil where the canal ispassing through (by giving test pit or auger hole data
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at about 500 m. intervals), value of In', bed width,
side slopes, full supply depth, freeboard, full supply
discharge, width of bank, L/R, velocity, C.V.R.,
losses etc. for various reaches.
viii) Location and type of cross drainage works with hy-
draulic details, e. g. catchment area, H. F. L., Dis-
char ge etc.' and loss of head provi ded at such C.D.
Works.
. 4. Cross-Sections:- Cross-Sections of canals, at intervals of
100 tn., specially for maximum cutting, maximum filling and
partial cutting-filling, extending to 100 m. on either side of
the centre line of the canal showing the following details,
be given:-
v) Profiles of banks suitably designed providi.ng adequate'
cover over saturation line assumed for the soils in
banking with details of the impervious core if provided.In9pection and non-inspection path details.
vii) For lined canals, details of lining and under-
drainage arrangement behind it conforming tothe relevant 1.S. Codes. .
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(b) Design of Canals: The following data may be given.
1. Trial pit or auger hole data indicating the nature of soil
met with along the alignment of the canal.
2. Transmission losses assumed -ill the main Canal, brancl?-es,
distributaries and minors in the unlined and lined channelsalongwith th,ejustification for their assumption.
3. Cut-off statement showing the details of discharge requiredfrom tail to head considering the requirements of the off-
taking channels and transmission losses etc.
4. Design calculations for adequacy of canal sections adopted
indicating details e. g. formula adopted, values of constants,designed slopes, velocities allowed, C.V. Ratios, F. S.depths, Free Board, bed 'width to depth ratio etc.
(c) Cross Drainage Works: The followin'g information may be
given.
1. L-Section and cross-sections of the drains, along with de-
tails of catchment areas, high flood discharge, observed
H. F. L. alongwith canal data at the point of crossing.
2. Test pit or bore hole data for deciding the. nature of found-ation of structure.
3. At least outline designs and drawings for a few typicalstructures. Designs should include waterway calculationsand other items of hydraulic design.
(d) Distribution system :. The following details may be given:
1. Plan showing alignment of the distribution system -withthe
commanded area of each distributary.
2. Calculation of "Design Discharge 11 of each distributary in-
clusive of transmission losses.
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3.1 On the watershed plan should be shown (a) the prominent
orographic features (b)n~rmal annual isohyets (c) location of rain.
gauge stations in and around the catchment (the source of rainfall
data should be indicated) (d) gauge and discharge sites and (e) inter-
state boundaries. A map of India showing annual normal rainfall is
enclosed as Appendix V.
3.3 Data and frequencies of. heavy rainfall in the catchment and
its neighbourhood should be collected and evaluated. Standard pro-
ject storm or maximum probable storm rainfall depths including
maximisation should be determined.
3.4 Climatic investigation for the project 'command should include
pan-evaporation data where available. If. however. this. is not avail-able. information on the following items may be collected.
4. Mean mon~hly temperature. Maximum and minimum monthly
temperature.sand maximum variation in daily temperatures
for each month should be observed.
3. 5 Ga~ge and discharge observatiolls (preferably by currentmeter) should extend for at least five years at the project site.Observed data for as many years as possible. should be collectedfor the nearest site on the same stream or for adjoining stream(s)with similar catchment characteristics. .)
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3.6 Sediment observations should be carried out for a period of
three years of the suspended load, bed. load and natural soil condi-
tions including catchment characteristics from the point of erosion.
The silt manual by c. S. M. Research Station of cwe may be refer-red to for further details.
3.6.1 Chemical and petrographic analysis of river water may be
examined and report maintained.
3.7 Gauges and discharges during flood occurrence should be ob-
served at short intervals say hourly and survey map of flood marks
of past floods.
ii) Estimation of annual yields and their break up into
monthly, monsoon and non-monsoon run-off.
iii) Actual 10-daily observed run-off pattern for run-off
the river projects.
iv) Estimated yields for reliabilities of 75%, 90% and
100%for irrigation, power and water supply projects
respectively.
v) Working tables for a representative cycle of years to
ascertain the percentage success of the project.
vii) The criteria to be followed in the estimation of design
flood for major and medium dams and other hydraulic
structure, are as follows:-
3.8. 1. 1 Major and medium dams: In the design of spillway for
major and medium projects {with storages more than 50,000 acre
ft.) the maximum probable flood which is the maximum flood for '-;}which there is a reasonable chance of occurring at the site should
be used. The method of estimation of the maxirn,um probable flood
is the one using the unit hydrograph principle and the maximum
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probable storm. The maximum probable storm is an estimate of
the physical upper limit to storm rainfall over a basin. It is ob-
tained from storm studies of all the storms that have occurred in the
region and maximising them for the mechanical efficiency of the
storm in changing water vapour and droplets in the atmosphere intorain and moisture content of the rain-producing air mass involved
in the storms. It has been the practice till now not to attemptmaximisation for mechanical efficiency of the storm due to insuffi-
cient knowledge of this factor; therefore for the present maximisa-
tion for moisture content need only be made.
3.8.1.2 The distribution of storm intensities for small durations
is obtained on the basis of recorded data of self-recording raingaugestations in the concerned catchment or region. The range of maxi-
misation of unit hydrograph peak should be taken between 0 to 50percent based on the discretion and judgement of the hydrologist.
If the unit hydrograph is derived from very heavy floods of con-
siderable volumes then the increase need be of a small order. Butif it is derived from low floods then the increase has to be sub-
stantial.
The rate of infiltration loss should be estimated from the
volume of flood run-off and the corresponding storm rainfall thatcaused the flood etc. and a minimum infiltration rate has to be
adopted.
3.8.1.3 The probability method when applied to derive design
floods for long recurrence intervals several times larger than the
length of data has many limitations. In certain cases. however.
like that of very large catchments where unit hydrograph method is
not applicable and where sufficient long term discharge data is
available. the frequency method may be the only course possible.
In such cases the design flood to be adopted for major structures
should have a frequency of not less than once in 1.000 years.
Where annual flood values of adequate length are available. they
are to be analysed by the Gumbel's method and where the data is
short either partial duration method or regional frequency technique
is to be adopted as a tentative approach and the results verifiedand checked by hydrological approaches.
Sometimes when the flood data is inadequate. frequency
analysis of recorded storms is made and the storms of a particular
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frequency applied to the unit hydrograph to derive the flood; this flood
usually has a return period greater than that of the storm.
3.8. 1.4 While planning there may be some projects where there is
hardly any discharge data available. In such circumstances for
preliminary studies the peak flood may be estimated by empirical
formulae. The empirical formula commonly use? in Central andNorthern India is the Dicken's formula Q = CA3 4 where A is the
catchment area in sq. miles and C is a constant. The constant
C varies widely; and it is subject to individual judgement its value
is of the order of 200 to 400 for plain catchment and 1000 to 2000
in the mountainous region according to catchment characteristics.In South India, Ryv's formula Q = CA3/4 is adopted, t:le value of
C being 450 in flat tracts along coast and it varies widely, being
of the order of 2,800 in the Western Ghat region. In Maharashtra:
Inglis-rbrmula Q = 7000 A and Q = 7000JA are generally
j A+4
used for small and big catchments respectively.
Since the probability method and the empirical approach
have their limitations and would give only the design peak discharge
and not the complete design flood hydrograph, the Commission areof the view that these methods be used provisionally and every effort
should be made to collect the required hydrological data at site and
obtain the design flood by rational methods (e. g. unit hydrograph
method) before the project designs are finalised.
3. 9 In the Case of Barrage and Minor Dams
In the case of permanent barrages, and minor dams withless than 50,000 acre ft. storages, the standard project flood or a
100-year flood, whichever is higher is to be adopted.
The standard project flood may be defined as a hydrograph
representing run off from the standard project storm. The standard
project storm is defined as one which is "reasonably capable" of
occurrence over the basin in question. This is not as definitive as
description as that for probable maximum storm. It may be takengenerally as the largest storm which haf occurred in the region of
the basin during the period of weather records. It is not maximi-
sed for most critical atmospheric conditions but it may be transposed
from an adjacent region to the watershed under consideration.
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3.10 The initial reservoir level before the impact of the spillway
design flood has to be taken as at full reservoir level. In regions
experiencing prolonged floods where storms can occur in quick
succession, design flood preceded or succeeded by a flood of once
in 25 years frequency should be considered. The interval between
these two floods (peak to peak) may be taken as 3 or 5 days accord-
ing to as the region lies in an annual rainfall zone of more than 40I'
or less than 40" respectively.
3.11 To provide for mechanical and other failures, it is neces-sary to assume some gates as inoperative with a maximum of 10 per
cent and minimum of one gate. For this purpose the designer may
be permitted to increase permissible stresses treating it as anextra-ordinary occurrence, like earthquake.
In the Case of Weirs, Aqueducts etc.
For pick-up weirs, a flood of 50-100 years frequency
should be adopted according to its importance and local conditions.
Waterways for canal aqueducts should be prOVided to pass
a 50-100 years flood, but their foundations and freeboard should befor a flood of not less than 100 years return period.
In case of cross drainage works, which carry highways or
railways, waterways provided should also satisfy the respective
standard code of practice of highways or railways.
3.13 Each site is individual in its local conditions, and evalua-
tion of causes and effects. While, therefore, the norms, mentioned
herein above, may be taken as the general guide lines, the hydrolo-
gist, and, the designer would have the discretion to vary the norms,
and the criterion in special cases, where the same are justifiable on
account of assessable and acceptable local conditions; these should
be recorded and have the acceptance of the competent authority.
1. Floods for various return periods where long termflood peak data are available.
II. Distribution of silt load in the reservoir and
estimation of total loss of reservoir space onaccount of silting.
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4.1 On topographical maps. to a scale of about 1/15000 of the
project command area grid squares of about 100 ha. for flat areas
and smaller grids where topography is undulating. should be estab-
lished. Soil map of India is appended at Appendix VI.
4.2 Rapid reconnaissance survey may be carried' out with tra-
verses about 2 km apart. Auger holes and profiles should be takenat the rate of two per sq. km. covering the whole of the commanded
area. Detailed soil survey should then be done for the problem
areas such as those with high water tables. which are saline /alkaliaffected and water-logged or have low permeability. For the prob-
lem area auger holes and profiles should be taken at the rate of oneper sq.km.
4.3 Soil sampling data should be collected upto a depth of about
3 m. Test pit method of sampling may cover about 5 to 10%of the
total command area.
4.4 Observation wells suitably spread over the command area
should be selected and water levels observed during monsoon andnon-monsoon months for about 5 years.
4.5 Location of pits. auger holes and observation wells should
be shown on the topographical map indicated in 4.1 above.
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Water samples should be taken of the surface and ground
water and tested for their quality.
The publication"Tecl:mical series 3-Section I: Soil surveyand land classification", April 1970 published by Union Department
of Food and Agriculture during 1970 may be referred to for detailed
procedure.
4. 7 Soil map of the corn.mand area and a table giving area inhaD for each soil group should be prepared. Area in haD falling
under each land irrigability class using standard land classification.system should be shown. A chart should show the criteria used instandard land irrigability classification with definitions of each land
class.
4.8 C2Eo~pingPattern
i) Present cropping pattern gIvmg area in haD under
different crops now grown with or without irrigationunder each soil group and their present yields should
be surveyed.
ii) Proposed cropping patterns glVlng area in haD under
different crops to be grown rmder different soil groupsand their expected yields should be determined in con-
sultation with the State Agriculture Department.
Duty and delta for each crop being irrigated in the neighbour-ing areas should be studied.
Irrigation Wat~..rReq~rements
Investigations shall be done to determine the irrigation
water requirements at the farm outlets in consultation with the StateAgriculture Department.
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The areas in the commanded areas of the project which
require drainage system must be selected in the first instance.
Accordingly pilot schemes may be framed and carried out after
making necessary investigations. The following measures may be
adopted in above regard:
Training of existing natural drains (nallahs)of water from shrubs, grasses and woods.
of the following operations:
to free the flowThis consists
2. Excavating new drains or regrading existing drains on the
sides of irrigation channels and roads.
3. Land levelling and construction of field drains with proper
slopes duly turfed to avoid erosion.
Design G~iJ~_ri~of the drainage system
Following points may be taken into consideration to determine
the capacity of the drains by the surface and sub-surface flows which
vary from State to State depending on the nature of soil.
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1. Intensity and Frequency of Rainfall
Intensity and frequency of railuall for. the design of drainage
channel may be taken as 'maximum rainfall of 3 da.ys duration. On
economic consideration the maximum intensity ,of rainfall should be
taken as corresponding to only 15 years return. In case of masonry
structures, it should be taken as corresponding to 50 years return.
The infiltration capacities of soils tend to vary from placeto place according to type of soil, land use, season of year, generalclimatic conditions. The infiltration loss rate for the different soils
may be taken as under:
~Arid areas, Rainfalll Semi arid & Sue' IHumid areas
~ upto 40 Cm. ~humid.)Rainfall 40 IRainfall 150 ems.Type ~ I to 150 Cms. I
t Fo- IFarm ~Fal- ~ 1 .70- ~Farml Fal- ~ Fo- IFarmlFal-J rest ILand J low ~rest ILandIlow Irest ILand Ilow
I
,Unit Centimetres/hour
Hilly &Fat
Clay soil. 0. 09 0. 07 0. 05 0. 07 0. 05 0. 04 0. 05 0. 04 0. 05
Clayeyloam or
blackcottonsoil. 0. 17 0. 13 O. 09 0. 13 0. 10 0. 07 0. 09 0. 07 0. 05
Silty
loam orloams. 0. 26 0. 20 0. 14 0. 20 0. 15 0011 0. 14 0. 11 0. 08
Sandy
loam orAlluvium 0. 55 0. 50 0. 20 0. 30 0. 22 0. 15 0. 20 0. 15 O. 12
SandySoils 0. 50 0. 40 0. 30 0. 40 0. 30 0. 20 0. 25 0. 20 0. 15
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3. Permissible depth and duration of submergence
Permissible depth and duration of submergence will vary
from crop to crop. It is considered reasonable to keep the periodof submergence limited to 10 days inclusive of days of precipitation
and depth of submergence limited to 2 ft.
From econOlnic consideration" the construction of drains
may be taken upby designLngfor 50%of the discharge worked out for
the areas.
'!ype of Sche.mes
The ,area requiring drainage system should be divided into
three types.
The areas which have been adversely affected due to rise of
watertable between 0 to L 5 In (0 to 5'). In this case natural
drains ulay be deepened so that 0.5 m to 0.6 m (1!to 2 ft.) depthof the drain is in pervious strata. The total depth of the drain may
vary from 2.5 m to 3 m (8 ft. to 10 ft.). The other artificialdrains Inay be taken 0.45 to 0.6 m (I' to 2') it, the pervious strata.
Some dug wells may also be provided for lowering the watertable.
Type II
In the area where watertable is between 1.5 rn to 3.0 m(5ft. to 10ft.) at present and is likely to rise as time passes.
It is p1"oposed to train the natural drains to the depth of 1.2 m to
1.8 m or upto pervious strata whichever is less and the artificial
drains proposed to be dug along the channels should be to the limitof 1.2 m to 1.8 m or upto the pervious strata whichever. is less. .'
In the area where watertable is below 3.0 m (10 ft.) the
natural drains may be trained to the depth of 1.2 m to 1.8 m or
upto pervious strata 'whichever is less and no artificial drains arerequired to be provided in that area.
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i) Present position of power supply in the region, systemloads, load factor, kWhgenerated per kWinstalled.
ii) Extent of firm power available fromthe scheme andalso from the grid after commissioning of the P1?nt,extent of secondary power etc.
iii) Details of major loads to be served, future peak andenergy demands, anticipated system load factor.
iv) Investigation regarding earth resistivity connectionwith sub-station designs.
v) The survey plan should cover an area sufficient to in-clude switchyard and alternative plant layouts andshould give contour at intervals of 5m. Lowwaterlevel, maximumobserVedflood level, rock outcropssand shoals etc. at the power house site will be indi-
cated therein.
vi) Maximumand minimummonthly temperature andmaximumvariation in daily temperatures for eachmonth shouldbe recorded.
vii) Chemical and petrographic analysis of river watershouldbe carried out and recorded.
6.1 A map showingthe location of the sources of constructionmaterial required withtransport facility to work site should begivenfor rock, coarse andfine aggregates, pozzolans if proposedto be manufactured locally, soil for use in earth dam, dykes etc.
6.2 An estimate of the quantities available at vari
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6.3 Reports on tests carried out on the various constructionmaterials. The test procedures and other details shall be as perthe relevant Indian Standarrls Specifications.
6.4 Following investigations are' to be done for establishingsuitability:
Concrete and Masonry Dams
a) Geological and related characteristics of aggregates,
including:
b) Investigations for the availability of natural and
artificial pozzolona with their characteristics.
i) Petrographic analysis of sand and rock samples;
ii) Grading and .physical tests of ~and and rocksamples to asses s their suitability as construc-tion materials;
a) Plans and sections should be made of the borrow areashowingthe location and logs of test pits spaced about150mapart and demarcating different types of soil.
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v) Triaxial shear tests withpore pressure measure-ments under OMCand saturation conditions
c
;
c) The sand and gravel to be used for filters should betested for suitability ,as for concrete aggregate.
Map(s) should be preparea showingthe followingfacilitiesduring construction and completion phases of the project:
a) Existing andproposed roads, water and rail routeswith information on load and size limitq.tions.
c) Sources for obtainingpower withtransmission linesroutes.
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'Re-routmg of the communication system where existingsystem is disrupted dueto the construction of theProject.
8.1 Planning of river diversion arrangements and investigations
for structures such as cofferdams~ diversion channels~diversiontunnels etc.
8.3 Construction plari.trequirements and plant planning ,vi.thparticular reference to supply of power~water~compressed airand other equipment required for construction.
Theplanning~construction and operation of irrigation hydro-electric /multipurpose projects have conside.rable impact on navigation~fish culture, wild life~recreational aspects and overall ecology ofthe affected regions. Someof these. aspects onthe ecology of theregion as well as the overall environment are irreversible in nature.It is, therefore, necessary that a careful evaluation is made ofthese impacts~ whether goodor bad before the project is undertakenand necessary measures are planned well in advance to mitigate,
wherever feasible~the adverse impacts.
The minimumsurveys and investigations required to be madeare indicatedbelow:-
The construction of dams/barrages may affect the migration
of fish. This aspect has to be examined in consultation with theappropriate department of the State Government and provision offish ladders or other measures, if feasible economically, wouldhave to be considered. Somerestrictions may also have to be
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imposed on fishing in the project areas. Owing to diversion of water
into canals, there may be modification in flow patterns and quantums
along the rivers Ichannels, and their effects on fishing downstream
should also. be evalu:ated.
Measures should be identified to reduce the quantity of the
trash fish and at the same time increase the availabiu.ty of qualityfish in the affected areas.
A survey plan of the areas likely to be submerged constitu-
ting as encroachment on wild life habitat as a result of the proposed
structure should be incorporated in the report. The report should
also indicate the area of reserve forest/wild life sanctuary/n~tionalpark, if any, that may come under sub-mergence as also the esti-
mate of the wild life population in the area proposed to be sub-
merged. The quantum of the forest area used as cover and grass-land used for grazing by animals in the area proposed to be sub-
merged should also be indicated, as also the details of such areas
in the remaining parts of the sanctuary/park. The report should
also discuss whether the area to be submerged is of any special
importance to wild life in their annual/ seasonal migration. Indica-tion should be given of the site of any islands that may be created
due to the formation of the lake as well as of the possibilities of
alternative proposals fqr relocation of the affected wild life in theregion. Wherever necessary, the cost of these should be provided
in the project estimate.
In case the problem of water-logging is serious, the
steps to be taken to mitigate problems due. to water logging shouldbe outlined.
The contents on these matters included in the project reportshould be framed in consultation with the appropriate department ofthe State Government dealing with forest and wild life. .
9.3 Historical and Cultural Repercussions
Sites of great historical and cultural importance should becarefully looked for during the investigations and where such sitescannot be av~ided, a complete inventory of these should be made
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and the aspect discussed in the project report. The report shouldalso deal with the feasibility of shifting such monuments to safe
areas nearby wherever this is feasible, and indicate the cost
thereof.
The project report should indicate
submerged is of outstanding scenic beauty.damage to this amenity of natural heritage
be indicated.
whether the area to be
If so, how best thecan be minimised should
9.4 Other Ecological Factors
Large hydraulic structures will result in modification in the
natural flow patterns of the rivers. The disturbances likely to be
caused to the natural conditions of the river by such modificationsshould be discussed in the report and the protection works, if any,needed to retain the river to its naturality as much as possibleshould be thought out and discussed in the report. Among the as-
pects which would need attention are: the silting/scouring in theriver bed; impact of flood problems; the salinity of the flow in the
river channel and other similar ecological factors.
Hydr~ulic structures provide the scope for augmenting mani-fold the water-based/recreation facilities, including sport fishing.
The project report should include a discussion on the scope of such
development.
The project report should also have a broad qualitative
assessment of the various benefits which would arise from the
implementation of the project, and discuss these in relation to theadverse effects, if any, to the overall ecology of the region by theconstruction of the project.
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ii!!!!E"~'!!!!!:'!"=-~=~-""""='!OW'~~"-:'-;-"'-"'====1t:;O==='===~~==7t"~~~:=~~=8~:~,= . . . . . . , . . . . . . , = = ~ ~ -= ~U ~ ~ ~ - = = ~ = --'w~~~~j--~-~'~-m : f I I
I i
INEHt>,
PRINCiPAL LfTHOLOGlGpL
t'-J D
--'76~
The territorial waters: of t(idj~e::.;:ccnGinto the sea to a dis:t;l rI ce of twelve nautic~ miles
measurEd from thE . app r op ri at e base l ine.
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tND\ASEISMTC. ZONES
5 A Y OF
BENGAL'
, .~Ol!llOfi TA 'k.sfisMJ C> ~;Clt-f:"FFlC'trg '!' < h
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APPENDIX III
SEISMIC COEFFICIENTS FOR SOME IMPORT ANT TOWNS
I IHorizontall I Horizontal
Town t ZoneI
Seismic I Town Zone I SeismicI ICoefficient I ICoefficienti1 h
Agra III 0. 04 Durgapur III 0: - 04
Ahmedabad III 0. 04 Gangtok IV 0. 05
Ajmer I 0. 01 Gauhati V 0. 08
Allahabad II 0. 02 Gaya III 0. 04
Almora IV 0. 05 Gorakhpur IV 0. 05
Ambala IV0. 05
Hyderabad I0. 01
Amritsar IV 0. 05 Imphal V 0. 08
Asansol III 0. 04 Jaipur II 0. 02
Aurangabad I 0. 01 Jamshedpur II 0. 02
Bahraich IV 0. 05 Jhansi I 0. 01
Bangalore I 0. 01 Jodhpur I 0. 01
Barauni IV 0. 05 Jorhat V 0. 08
Bareilly III 0. 04 Jabalpur III 0. 04
Baroda III0. 04
Kanpur III0. 04
Bhatinda III 0. 04 Kathmandu V 0. 08
Bhilai I 0. 01 Kohirria V 0. 08
Bhopal II 0. 02 Kurnool I 0. 01
Bhubneshwar III 0. 04 Lucknow III 0. 04
Bhuj V 0. 08 Ludhiana IV 0. 05
Bikaner III 0. 04 Madras II 0. 02
Bokaro III . 0. 04 Madurai II 0. 02
\Bombay III0. 04
Mandi V0. 08
Budwan III 0. 04 Mangalore III 0. 04
Calcutta III 0. 04 Monghyr _ IV 0. 05
Calicut III 0. 04 Moradabad IV 0. 05
Chandigarh IV 0. 05 Mysore I' 0. 01
Chitradurga I 0. 01 Nagpur II 0. 02
Coimbatore III 0. 04 Nainital IV 0. 05
Cuttack III 0. 04 Nasik III 0. 04
Darbhanga V0. 08
Nellore II0. 02
Darjeeling IV 0. 05 Panjim III 0. 04
Dehradun IV 0. 05 Patiala III 0. 04
Delhi IV 0. 05 Patna IV 0. 05
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I t Horizontal 0 t o HorizontalTown IZone ISeismic I Town I Zone ISeismic
I ICoefficientI I ICoefficient '-h h
Pilibhit IV . 0. 05 Srinagar V 0. 08
Pondicherry II 0. 02 Surat III 0. 04Poona III 0. 04 Tezpur V 0. 08Raipur I 0. 01 Thanjannur II 0. 02Rajkot III 0. 94 Trichunapalli, II 0. 02Ranchi II 0. 02 Trivandrum III 0. 04Roorkee IV 0. 05 Udaipur II 0. 02 . "ROurkela I O. ' 01 Varanasi II 0. 02Sadiya V 0. 08 Vijaywada III 0. 04
Simla IV 0. 05 Visakhapat- II 0. 02Sironj I 0. 01 nam
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No.DW-l1-11(8)!68Government' of India
Ministry of Irrigation and Power
Subject: Allowance for Seismic Forces in the Design of River
Valley Projects, Setting up of a Standing Committee.
After the Koyna earthquake, the necessity has been felt
for a high level inter-disciplinary official body to advise on the de-sign Seismic co-efficients for dams and other structures of Irriga-
tion and Power projects. In consultation with the Ministries of
Tourism and Civil Aviation and Petroleum, Chemicals, Mines and
Metals (Department of Mines and Metals) Standing Committee of
the following composition is hereby constituted:
Member (D&R). Central Water &
Power Commission
Director, Seismology, Indian
,Meteorological Department,
New Delhi
Shri V. S. Krishnaswamy,Director, Engineering Geology,
Division, Geological Survey
of India, Northern Region,Calcutta
The Standing Committee will meet periodically as required
and advise the various authorities on matters referred to it.
Sd/- N.C.Saksena
23. 6. 1969
Joint Secretary to the Govt. of India.
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I ND I A
A N NU A L N ORM A L RA I NF A L L
I ' A R A B I ANSEA
BAYOF
BENGAL
E I 'J > '~ PORT 8LAIR_% (i
-III
~~ ,- (\ ,~0'/I
---------' '\~
\~().~
rJ > ' .711:' I,. .U I
-%'%1>00
~ ~ - T R I V A N D. . . '"
"1l
The territorial waters of lodiaextend into the sea to distance of twelve nautical miles
measured from the appropriate baseline.
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F-----i ,-_ _ 6 ' ~- - - -j 1o~l -i~-- -- 72;' I~_ - - - r - - -! I
III
II 'i.r
iJ 2 .
i, I
- I I II,
ilf
-- - - "i ----.--~.I
_ 92"- - - . --I
INDIASOiL M A P
(
PAKISTAN
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