Development of Hydrological Design Aids for Water Resources Projects

Project: Development of Hydrological Design Aids (Surface Water) under HP-II
Document: 2009097/WR/REP-02 July 2010
State of the Art Report Revision: R0
i WATER RESOURCES

Contents
EXECUTIVE SUMMARY..................................................................................................... ES-i to x
CHAPTERS
1. INTRODUCTION 1-1
1.1 Background of the Project................................................................................. 1-1
1.2 Need for Development of HDAs....................................................................... 1-1
1.3 Hydrological Studies Required for a Water Resources Project......................... 1-2
1.4 Design Parameters for Development of HDA................................................... 1-3
1.5 Scope and Methodology for the Consultancy.................................................... 1-5
2. PREVALENT DESIGN CRITERIA AND PRACTICES: THE INDIAN
PERSPECTIVE......................................................................................................... 2.1-1
2.1 Assessment of Water Resources Potential – Availability / Yield Assessment.. 2.1-1
2.1.1 Approach…………………………………………………………. 2.1-1
2.1.2 Hydrological data type and extent of hydrological inputs………... 2.1-1
2.1.3 Compilation and Hydrological Data Processing…………………. 2.1-2
2.1.3.1 Filling of short data gaps…………………………………………. 2.1‐2
2.1.3.2 Adjustment of records……………………………………………. 2.1-3
2.1.3.3 Consistency of data………………………………………………. 2.1-5
2.1.3.4 Data Extension…………………………………………………… 2.1-6
2.1.3.5 Data Generation…………………………………………………... 2.1-7
2.1.4 Water Availability Assessment…………………………………... 2.1-7
2.1.5 Continuous simulation Models / related data processing model
developed in India……………………………………………….. 2.1-8
2.1.5.1 HYPRO package………………………………………………….. 2.1-8
2.1.5.2 Water Yield Model (WYM)……………………………………… 2.1-8
2.1.6 Rainfall-Runoff Models developed for some regions in India…… 2.1-9
2.1.7 Design Practices adopted by State Government for yield
estimation in India……………………………………………….. 2.1-11
2.1.8 State-of-the-Art technology developed in various parts of the
world and applied in Indian catchments by various Premier
Research Institutes of India……………………………………… 2.1-13
2.1.9 Snowmelt Hydrology…………………………………………….. 2.1-16
2.1.9.1 Introduction………………………………………………………. 2.1-16
2.1.9.2 Snowmelt Modelling……………………………………………... 2.1-16
2.1.9.3 SWAT snowmelt hydrology……………………………………… 2.1-19
2.2 Estimation of Design Flood…………………………………………………… 2.2-1
2.2.1 General……………………………………………………………. 2.2-1
2.2.1.1 Objectives of Design Flood Estimation…………………………... 2.2-1
2.2.2 Literature Review………………………………………………… 2.2-1
2.2.2.1 General……………………………………………………………. 2.2-1
2.2.2.2 Previous Practices in India……………………………………….. 2.2-2
2.2.2.2.1 Project Categorization……………………………………………. 2.2-2
2.2.2.2.2 Empirical Formulae………………………………………………. 2.2-2
2.2.2.2.3 Rational Formula…………………………………………………. 2.2-3
2.2.2.3 Current Design Flood Estimation Criteria/Practices……………... 2.2-3
2.2.2.3.1 General……………………………………………………………. 2.2-3
2.2.2.3.2 Central Water Commission (CWC)………………………………. 2.2-3
2.2.2.3.3 Bureau of Indian Standards (BIS)………………………………... 2.2-17
2.2.2.4 Design Flood Estimation Approaches……………………………. 2.2-18
2.2.2.4.1 Flood Formulae…………………………………………………… 2.2-18

ii WATER RESOURCES

2.2.2.4.2 Probabilistic/Statistical Approach (Index Flood Method)………... 2.2-19
2.2.2.4.3 Hydrometeorological Approach………………………………….. 2.2-21
2.2.2.4.4 Regional Flood Frequency Analysis……………………………… 2.2-22
2.2.2.5 Estimation of Snowmelt Contribution……………………………. 2.2-23
2.2.2.5.1 GLOF……………………………………………………………... 2.2-26
2.2.2.6 Design Flood for Urban and Agricultural Catchments…………… 2.2-30
2.2.2.6.1 Urban Catchments………………………………………………... 2.2-30
2.2.2.6.2 Agricultural Catchments………………………………………….. 2.2-30
2.2.2.7 Climate Change Effects…………………………………………... 2.2-32
2.2.3 Reviews and Recommendations………………………………….. 2.2-32
2.2.3.1 Suggested Design Flood Estimation Criteria…………………….. 2.2-32
2.2.3.2 Procedures for determining PMF………………………………… 2.2-33
2.2.3.3 Procedures for determining T-Year Flood………………………... 2.2-33
2.2.4 Conclusions………………………………………………………. 2.2-34
2.3 Sedimentation Rate Estimation………………………………………………... 2.3-1
2.3.1 Introduction………………………………………………………. 2.3-1
2.3.2 Silting Rate for Planning Indian Reservoirs……………………… 2.3-1
2.3.2.1 Direct Measurement of Sediment in River……………………….. 2.3-1
2.3.2.2 Reservoir Capacity Survey……………………………………….. 2.3-2
2.3.2.2.1 Modern Techniques of Surveying: HYDAC 3 (Hydrographic data
Acquisition system)……………………………………………… 2.3-3
2.3.2.2.2 Remote Sensing…………………………………………………... 2.3-3
2.3.2.3 Results from River/Reservoir Sediment Data……………………. 2.3-3
2.3.2.4 Prediction of Rate of Reservoir Sedimentation………………….. 2.3-6
2.3.2.5 GIS Applications for Determination of Sediment Yeild…………. 2.3-8
2.3.3 Trap Efficiency…………………………………………………… 2.3-9
2.3.4 Predicting Sediment Distribution in Reservoir…………………… 2.3-9
2.3.5 Life of Reservoirs………………………………………………… 2.3-10
2.3.6 Planning Practices for Reservoir Sedimentation in India………… 2.3-10
2.3.7 Practices Adopted By State Governments………………………... 2.3-13
2.3.8 Conclusion……………………………………………………….. 2.3-14

3. PREVALENT DESIGN CRITERIA AND PRACTICES:
THE INTERNATIONAL PERSPECTIVE……………………………………… 3-1
3.1 Assessment of Water Resources Potential – Availability / Yield Assessment.. 3-1
3.1.1 Approach to the assessment of Water Resources Potential………. 3-1
3.1.2 Climate change impacts on river flows…………………………... 3-6
3.1.3 Data requirements & data management…………………………... 3-6
3.1.4 Rainfall-runoff modelling………………………………………… 3-36
3.1.5 Water resources system modelling……………………………….. 3-36
3.1.6 River basin modelling……………………………………………. 3-37
3.1.7 Snow melt runoff modelling……………………………………… 3-38
3.1.8 Glacier melt runoff modelling……………………………………. 3-50
3.1.9 Recommendations………………………………………………... 3-53
3.1.10 References………………………………………………………... 3-54
3.2 Estimation of Design Flood………………………………………………….. 3-61
3.2.1 Approach to Design Flood Estimation (hydro-meteorological;
statistical; regional)……………………………………………… 3-61
3.2.2 Overview of Methods for Estimation of the Design Flood………. 3-68
3.2.3 Estimation of Hypothetical Floods……………………………….. 3-69
3.2.4 Estimation of Probabilistic Floods……………………………….. 3-72
3.2.5 Regional Flood Frequency Analysis……………………………… 3-76
3.2.6 Flood Wave Propagation…………………………………………. 3-77
3.2.7 Impact of snow melt contribution on Design Flood
(Includes GLOF and cloud burst flood)…………………………..
3-78

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3.2.8 Development of Design Flood Hydrograph for Agricultural
and Urban catchments…………………………………………….
3-79
3.2.9 Stationarity, trend and climate change…………………………… 3-79
3.2.10 Glossary…………………………………………………………... 3-81
3.2.11 References………………………………………………………... 3-83
3.3 Sedimentation Rate Estimation……………………………………………….. 3-87
3.3.1 General Concepts…………………………………………………. 3-87
3.3.2 Availability of Standards and Guidance………………………….. 3-89
3.3.3 Current Practice is different in different parts of world………….. 3-89
3.3.4 Historic development of reservoir sedimentation methods………. 3-90
3.3.5 Estimation of sediment yield……………………………………... 3-91
3.3.6 Assessment of sedimentation rates………………………………. 3-96
3.3.7 Increasing emphasis on mitigation methods……………………… 3-100
3.3.8 References………………………………………………………... 3-101
4. PROPOSED HYDROLOGICAL DESIGN PRACTICES……………………… 4-1
4.1 General……………………………………………………………………….. 4-1
4.2 Assessment of water resources potential – availability (HDA1)…………….. 4-1
4.2.1 Criteria With Checklist for choosing an established tool………… 4-2
4.2.2 Recommended Procedure………………………………………… 4-4
4.2.2.1 Pre-processing Functions………………………………………… 4-4
4.2.2.2 Techniques for Filling in Missing data…………………………… 4-4
4.2.2.3 Consistency test functions………………………………………... 4-5
4.2.2.4 Hind-casting of stream flow records where Precipitation data is
Available…………………………………………………………. 4-5
4.2.2.5 Synthetic flow Generation………………………………………... 4-6
4.2.2.6 Naturalisation of Flow……………………………………………. 4-6
4.2.2.7 Rainfall Runoff Modelling……………………………………….. 4-7
4.2.3 Proposed Models-Description & Data Requirements……………. 4-12
4.3 Design flood Estimation (HDA2)…………………………………………….. 4-13
4.3.1 General……………………………………………………………. 4-13
4.3.2 Estimation of PMF & SPF & T-year Flood………………………. 4-13
4.3.3 Urban & Agriculture Catchments………………………………… 4-17
4.3.4 Road Map for Design Flood Estimation (HDA-2)……………….. 4-18
4.4 Sediment Rate Estimation (HDA-3)………………………………………….. 4-22
4.4.1 Estimation of Sediment Yield…………………………………….. 4-22
4.4.2 Distribution of Sediment in reservoir…………………………….. 4-23
4.4.3 Proposed Road Map (HDA-3)……………………………………. 4-24
TABLES
Table 2.1 Rainfall runoff ratios for different surface conditions…………………….. 2.1-9
Table 2.2 Commonly used formulae………………………………………………… 2.2-2
Table 2.3 Decisive Parameters for Various purposes………………………………... 2.2-4
Table 2.4 Design Flood Values……………………………………………………… 2.2-6
Table 2.5 Comparison of Design Criteria……………………………………………. 2.2-8
Table 2.6 Comparison of Procedures for Design Flood Estimation…………………. 2.2-9
Table 2.7 Consequence Classification of Dams……………………………………... 2.2-12
Table 2.8 Synthetic UG Relations for Small/Medium Catchments………………….. 2.2-14
Table 2.9 Regional Flood Formulae for Small/Medium Catchment………………… 2.2-15
Table 2.10 Comparison of Goodness of fit Tests……………………………………... 2.2-20
Table 2.11 Comparison of Snowmelt Runoff…………………………………………. 2.2-25
Table 2.12 Characteristics of identified urban runoff models………………………… 2.2-31
Table 2.13 Region wise Sedimentation Rate in India…………………………………. 2.3-4
Table 3.1 Main data types used in water resources assessment……………………… 3-13

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Table 3.2 Hydraulic models and their data requirements……………………………. 3-15
Table 3.3 Types of data to which QAS apply………………………………………... 3-16
Table 3.4 Description of the steps taken for each level of quality assurance………... 3-17
Table 3.5 Guidelines for limits of infilling data where gaps or errors exist…………. 3-19
Table 3.6 Example methods of correcting or infilling gaps in data, their suitability
and application……………………………………………………………. 3-21
Table 3.7 Details relating to catchments, catchment observed-flow series (gauged
and naturalised) and model calibration periods…………………………... 3-29
Table 3.8 Form for identification of character of a catchment (Environment
Agency, 2001)……………………………………………………………. 3-33
Table 3.9 Advantages and disadvantages of the two main approaches to melt
Modelling…………………………………………………………………. 3-43
Table 3.10 Application of various sensors for particular snow properties……………. 3-46
Table 3.11 Classification of Water Conservancy and Hydropower Projects in China... 3-62
Table 3.12 Classification of hydraulic structures in China……………………………. 3-63
Table 3.13 Design flood criteria for permanent structures in China………………….. 3-63
Table 3.14 Check design flood criteria for permanent structures in China…………… 3-63
Table 3.15 Design flood and Check design flood criteria for powerhouse and
non-damming structures in China………………………………………… 3-64
Table 3.16 Design flood criteria for temporary structures in China…………………... 3-64
Table 3.17 French dam safety assessment criteria……………………………………. 3-64
Table 3.18 Polish dam safety assessment criteria…………………………………….. 3-66
Table 3.19 UK dam safety assessment criteria………………………………………... 3-67
Table 3.20 US Federal recommended spillway design floods………………………… 3-68
Table 4.1 Checklist Matrix for Rainfall –Runoff models…………………………… 4-2
Table 4.2 Checklist Matrix for Water resources system models…………………….. 4-3
Table 4.3 Checklist matrix for River Basin models…………………………………. 4-4
FIGURES
Figure 2.1 Schematic diagram of monthly runoff model……………………………... 2.1-17
Figure 2.2 Simplified flow chart of vertical balance within each ASA………………. 2.1-19
Figure 2.3 Sub-Zonal Map of India for Small/Medium Catchments flood studies…... 2.2-16
Figure 2.4 Map of India showing zone wise sedimentation rate……………………… 2.3-5
Figure 2.5 Iso-erosion rate (in Tonnes km-2yr-1) map of India (Garde and
Kothyari,1987)…………………………………………………………… 2.3-8
Figure 3.1 Locations of the 15 catchments used in Jones et al. (2006)……………… 3-28
Figure 3.2 Reconstructed and measured river flow on the River Exe from 1907-11… 3-31
Figure 3.3 fundamental operations involved in modelling snowmelt………………... 3-40
Figure 3.4 Generalized depositional zones in a reservoir…………………………….. 3-88
Figure 3.5 Formation of fluvial delta in Lake Mead, USA – Smith et al (1954)……... 3-88
Figure 3.6 Average annual sediment yield versus drainage area for semiarid areas of
the United States (Strand and Pemberton 1987)…………………………. 3-90
Figure 3.7 Sediment yield map for India (Shangle, 1991)……………………………. 3-93
Figure 3.8 Relationship between reservoir hydrologic size (capacity: inflow ratio)
and sediment-trapping efficiency by Brune and the Sedimentation index
approach by Churchill (Strand and Pemberton 1987)………………….. 3-97
Figure 3.9 Churchill curve for estimating sediment release efficiency
(adapted from Churchill 1948)…………………………………………… 3-97
Figure 3.10 Temporal development of delta growth upstream of Bakra Dam, India.
The rate of delta advance slows with time because Of the reservoir
geometry, which depends and broadens in the downstream direction…… 3-99

v WATER RESOURCES

ANNEXURES
Annexure 2.1: Classification of Projects based the Type of Structure and on the
Contemplated Use of Water
Annexure 2.2: Commonly Used Methods for Consistency Tests
Annexure 2.3: Yield Estimation - Guideline for the Preparation of Preliminary
Water Balance Reports, NWDA, GOI, Nov 1991
Annexure 2.4: Yield Assessment - Manual on Planning and Design of Small
Hydroelectric Schemes, CBIP, India, 2001
Annexure 2.5: Yield Assessment - Hydrological Aspects in Project Planning and
Preparation of DPR, Training Directorate, CWC
Annexure 2.6: Model Structure of Water Yield Model (WYM)
Annexure 2.7: SHE Model
Annexure 2.8: SCS – CN Based Hydrological Model
Annexure 2.9: Tank Model
Annexure 2.10: Lumped Basin scale Water Balance Model
Annexure 2.11: SWAT Model
Annexure 2.12: Artificial Neural Networks in Rainfall – Runoff Modelling
Annexure 2.2-1: Practices by State Governments
Annexure 2.2-2: Flood Formulae
Annexure 2.2-3: Probabilistic approach for estimation of design flood
Annexure 2.2-4: Deterministic or Hydrometeorological approach for estimation of design
flood
Annexure 2.2-5: Regional flood frequency analysis (Ungauged Catchments)
Annexure 4.1: SWAT Model
Annexure 4.2: Water Rights Analysis Package (WRAP)
Annexure 4.3: HEC-HMS Soil Moisture Accounting (SMA) Model
Annexure 4.4: Model E
Annexure 4.5: HEC-RESSIM
Annexure 4.6: Snowmelt Runoff Model WINSRM
APPENDICES
Appendix A Step-by-step guide to extending hydrological data
Appendix B Snow melt model summaries
Appendix C Case studies of snow melt model application and use
Appendix D Rainfall-runoff model summaries
Appendix E Hydraulic model summaries

ES - i WATER RESOURCES
Executive Summary
Hydrology Projects I and II aim to ‘support major aspects of India’s National Water Policy,
particularly with regard to water allocation, and the planning and management of water resources
development at the national, state, basin, and individual project levels.
Hydrology Project-II is a sequel to its predecessor, Hydrology Project-I, which aimed to improve
hydrometeorological data collection procedures in nine states and six central agencies. Hydrology
Project-II builds upon the earlier project’s Hydrological Information System, through broadening the
area of application to thirteen states and eight central agencies, and through various ‘vertical
extension’ activities such as the current project. This project aims to develop Hydrological Design
Aids to improve upon current design practices and to standardise those practices for uniform use all
over the country. One of the first steps in enabling the development of such Hydrological Design Aids
is to assess the current, relevant, state-of-the-art in tools and techniques used in India and around the
world, and to review the international state-of-the-art with a view to transferring those tools and
techniques for use in India.
This report reviews the state of the art in the three key study areas: assessing water resource
availability; estimating the design flood; and sedimentation rate estimation. The assessment is
undertaken for the international context with reference to applicability in India.
The main purpose of this review of the state-of-the-art in the three key study areas is to inform the
process of development of three Hydrological Design Aids, one for each of those key study areas. The
international state of the art is reviewed to enable a comparison with the procedures currently being
carried out in India, and to help identify those techniques which would offer an improvement over
current methods and that could sensibly be transferred for use in India. The report makes specific
recommendations of those internationally employed tools and techniques that the authors believe to be
suitable for use in India.
The three matrices below (Tables 0.1-0.3) summarise the findings of the report. There is one matrix
per Hydrological Design Aid. Each matrix presents the tools and techniques for the Indian and
international contexts, grouped according to their areas of application. Each matrix, and each area of
application, also presents a priority for those tools and techniques that could sensibly and usefully be
employed as part of each Hydrological Design Aid under this project.
Table 0.1:Summary of state of the art techniques & tools used in assessment of water resources
potential
Area of application
of techniques &
tools
Techniques & tools
used in Indian context
Examples of techniques &
tools used in international
context
Priority areas for
further work
(High to Low)
(Low means that
Indian methods
are ‘state of the
art’)
Project pre-feasibility
stage
Strange’s Table
Observed flow
Empirical formulae
ICAR formula for small
watersheds
Thorrnthwaite Mather’s
formula
Empirical calculations to
estimate seasonal flows, mean
flow and low flows
Rainfall-runoff models,
HYSIM
Water resource systems
models
High

ES - ii WATER RESOURCES
Area of application
of techniques &
tools
Techniques & tools
Examples of techniques &
tools used in international
context
Priority areas for
further work
(High to Low)
(Low means that
Indian methods
are ‘state of the
art’)
AQUATOR
HEC-ResSim
River basin models, e.g.
MIKE BASIN
WRAP
IRAS
Project design stage Observed flows
Rainfall Runoff models
Regression
relationship
Snowmelt model
Simple conceptual
model - Degree day
method
SLURP model
Rainfall-runoff models
PDM
CatchMOD
HEC-HMS
IHACRES
HYSIM
NAM
SHE
SWAT
Hydraulic models
InfoWorks RS
InfoWorks ICM
Mike 11
SOBEK
Snow melt runoff models
Temperature-index
models HBV
SRM
SNOW-17
Energy balance approach
PRMS
SSARR- energy budget
method
Combined approach
NWS RFS
UBC Watershed model;
PREVAH.
Glacier melt runoff models
SRM-ETH;
WaSiM-ETH
HBV (glacier module)
High

ES - iii WATER RESOURCES
Table 0.2:Summary of state of the art techniques used in the estimation of design flood
Area of
application of
techniques
and tools
Techniques and tools
Techniques and tools used in
international context
Priority areas for
further work (
High to Low)
(Low means that
Indian are ‘state
of the art’)
Recommended
Approach
Spillways of major and
medium dams:
maximum probable
flood as derived using
unit hydrograph and
maximum probable
storm. Where Annual
Maximum flood series
is available, Probability
distribution methods
like Log Normal(2 and
3 parameters), Pearson,
Log Pearson and
Gumbel for 10000 year
flood are used.
Barrages and minor
dams: standard project
flood (SPF)/500 yr flood
for free board, 50 yr
flood for remaining
aspects
Miscellaneous hydraulic
structures: 50-100 year
flood to be used
ICOLD: PMF as design standard
for large dams;
Australia: PMF-DF is design
flood for which probability of
flood=probability of rainfall;
Canada: PMP for large dams,
WMO procedures as per
Operational Hydrology Report
No. 1
China: 5 project ranks
based on scale, benefit &
importance to economy;
France: H√V (H= dam height, V
= storage capacity);
Germany: Spillway capacity fro
large dams=1000 yr flood;
Iran: 24 hr PMP estimates are
derived using statistical analysis
with a frequency factor of 9.63.
For basins of 1000 sq km and less
the statistical estimates are used
while for larger basins the
estimated derived on physical
basis are used.
Japan: For concrete dams larger
of,
200 yr flood at site
Maximum experienced at site
Maximum that can be expected
1000 yr flood for embankment
dams
Kenya: WMO recommended
procedures
Malaysia: PMF derived from
PMP;
Norway: Spillway capacity for
Low
Low
Low

ES - iv WATER RESOURCES
Area of
application of
techniques
and tools
Priority areas for
further work (
High to Low)
(Low means that
Indian are ‘state
of the art’)
large dams=1000 yr flood;
Poland: Dams classified according
to foundation & potential
consequences;
Sweden: Large dams designed
according to pessimistic
assumptions about precipitation,
snow-melt & soils;
UK: Dams in 4 categories with
various design standards;
USA: Spillway design according
to hazard and size class
Estimation of
hypothetical
floods
Determination by
Empirical formulae
1. Formulae involving
drainage area only:
i. Dicken’s Formula
ii. Ryve’s Formula
iii. Ingis
iv. G.C. Khanna
v. Nawab Jung Bahadur
Formula
vi. W P Creager’s
Formula
total runoff and drainage
area:
i. Boston Society of
Civil Engineers Formula
rainfall intensity and
drainage area:
i.Rational Formula
rainfall and drainage
area:
Unit Hydrograph;
SCS method;
Probable Maximum Flood;
Probable Maximum Precipitation;
Continuous Simulation;;
Distributed catchment modeling
(Topmodel, HBV, Lisflood,
PDM, Catchmod)
High

ES - v WATER RESOURCES
Area of
application of
techniques
and tools
Priority areas for
further work (
High to Low)
(Low means that
Indian are ‘state
of the art’)
i. Graig’s Formula
Determination using
envelope curves – one
for south India, another
for Central/North India.
Upper curves
corresponds to world
records, average line
and lower envelope
curves for PMF peaks
developed by CWC and
other organizations
PMP, SPS, PMF
Hydrometeorological
approach
Estimation of
Probabilistic
Floods
Gumbel’s Method
Selection of frequency
distribution (Log
Normal(2 and 3
parameters), Pearson,
Log Pearson and
Gumbel);
Plotting rules for
observations;
Parameter fitting
(Graphical, Least
squares, Max likelihood,
PWM, L-moments);
Goodness of fit tests
Choice of statistic (AM, POT)
Selection of distribution (Normal,
Lognormal, Gumbel, GEV, Log-
Pearson III);
Plotting rules for observations;
Parameter fitting (Graphical,
Least squares, Min variance, Max
likelihood, PWM, L-moments);
QdF methodology;
High
Regional
Flood
frequency
analysis
CWC analysis of small
catchments for various
hydro meteorological
zones of India
Use of L-moments for
RFFA based on
available data.
Index flood method
Index flood methods based on
data availability and complexity;
Regional growth curves.
Determination of homogeneous
regions
High

ES - vi WATER RESOURCES
Area of
application of
techniques
and tools
Priority areas for
further work (
High to Low)
(Low means that
Indian are ‘state
of the art’)
Assessing the
impact of
snowmelt
contribution
GLOF by CWC
Empirical Relationship
GLOF: use techniques similar to
dam break assessment for high
risk glacial lakes
SRM model for snowmelt
contribution
High
Development
of design flood
hydrograph for
agricultural &
urban
catchments
No standardized
methodology exists.
Rational Formula
Use SCS
Where no standardized
methodology exists (e.g. FEH in
UK), use SCS
HEC-HMS kinematic wave
model
High
Table 0.3:Summary of state of the art techniques used in sedimentation rate estimation
Area of application
of techniques & tools
Techniques & tools used
in Indian context
Techniques & tools used
in international context
Priority areas for
further work (High
to Low) (Low means
that Indian methods
are ‘state of the
art’)
Estimation of
sediment yield
Maps of sediment yield in
various regions of India.
Sediment rating curves
Universal soil loss
equation
Delivery ratio
Reservoir surveys
SWAT (used by
researchers)
Global maps of sediment
yield
Sediment rating curves
Soil Loss Equations:
USLE, MUSLE, RUSLE
Delivery Ratio
Spatially distributed
models: AnnAGNPS,
HSPF, MIKE-SHE,
SWAT
High
Assessment of
sedimentation rates
Churchill / Brune curves Empirical relations for
trapping efficiency
(Churchill/Brune curves)
Numerical sedimentation
modelling: 1D
(RESSASS , Mike 11,
InfoWorks, HEC-RAS)
and 2D & 3D models
High

ES - vii WATER RESOURCES
The tables given above present specific tools for use at particular points in a typical project. Figure 0.1
presents a typical engineering project cycle, such as for reservoir design, for example. It shows the
main stages of the project, from concept through pre-feasibility and feasibility studies, on to detailed
design and engineering, then operational monitoring and finally evaluation. The figure shows the
main stages of the project cycle which would use the types of tools and techniques presented in this
state of the art report.
Figure 0.1 Project cycle diagram showing types of tools and techniques used at each stage of a
typical project
This report considers the data necessary for hydrological assessment of water resources availability
and yield and methods of adjusting these data, including gap-filling and extending of time series. It
goes on to describe the various options available for modelling and forecasting of water resources
including in those areas affected by flows from snow and glaciers – there are clearly large and
important basins in India to which this applies. The report does not claim to be comprehensive in
terms of considering all options available worldwide, as there are an extremely large number of tools
which have been developed while only a small number are in widespread use. Rather, the report is
intended to give a summary of the major tools in use and in some cases relating to data management,
examples of standard practice from the UK as an example of best practice internationally.
The sections on design flood estimation and estimation of sedimentation rate are less extensive, being
smaller areas of research internationally and depending to some extent on the water resources data and
data management techniques described in the first section.
The review of Indian practices being followed at present vis-à-vis International practices as
summarised in the three matrices above indicates that a large number of models / practices could be
attempted in Indian scenario if the information base was available. Keeping in view the available data
in India through the Water Resources Information System (WRIS) being developed by CWC, HIS
system developed under HP-I, Survey of India topographical sheets, Thematic maps of soils from
National Bureau of Soil Survey, Agricultural Report from All India Soil and Land Use Survey and
other data from Directorate of Land Use and Land Records, National Thematic Mapping Organisation

ES - viii WATER RESOURCES
and Indian Meteorological Department, the following techniques are recommended in the three study
areas.
A. Assessment of Water resources potential – availability (HDA-1)
Processes Tools suggested
Flow naturalisation WRAP,
NWDA Water Balance method (in house)
Synthetic Flow Generation AR, MA, ARMA, Seasonal
ACF and PACF Analysis
Data validation Precipitation
Graphical Plot of Data for multiple stations for
checking spatial variability
Double Mass Curve
Discharge
Graphical Plot of Discharge with time
Graphical Plot of discharge with respect to any
adjacent basin upstream or downstream (if
homogenous) / rainfall
Residual series plot
Trend line Plot
Moving Average
Flow Mass curve
Student t – test and f – test
Data gap infilling Interpolation by extending a trend between the
recorded data points either side of the gap e.g.
exponential decay during low flows
Simple bridging using a straight line
Using spline technique to insert a curved line
that can be used for inserting peaks / troughs
Hind-casting of flow data with
Rainfall-Runoff modelling
MWSWAT,
Thornthwaite-Mather model
HEC-HMS
Regression Techniques
Water resources system
modelling
Hec ResSim
River basin modelling WRAP
Snowmelt runoff modelling
(including segregation into
rainfed and snowfed, seasonal
and permanent snowline,
rainfall and snowfall
characteristics)
WINSRM / MWSWAT
Glacier melt runoff modelling SRM
Technique for assessing the
potential impact of climate
change
MWSWAT

ES - ix WATER RESOURCES
B. Assessment of Design Flood (HDA-2)
Type of
Basin
Approach
suggested
Tools/Models suggested
Gauged
Basins
Hydrometeo
rological
approach
i. Tool for development of response function for basins of
size less than 5000 km2 which will include determination
of T-hour unit hydrograph using storm event and
concurrent discharge values, Collin’s method, Nash model,
Clark model.
ii. Tool for storm analysis which includes determination of
depth area duration curves, guidelines for storm
transposition, storm maximization, barrier adjustment and
development of storm hyetograph.
iii. Tools for IDF curve analysis.
iv. Tool for determination of Parameters of Muskingum Cunge
method of channel routing
v. SRM model for snowmelt contribution
vi. HEC-RAS model for GLOF routing. Separate tool will be
developed for routing in steep slopes.
vii. Tool for integrating GLOF with the intermediate catchment
runoff.
viii. For computation of flood hydrograph HEC-HMS model
have been identified
Probabilisti
c Approach
i. Tools for data mean, SD, skewness, kurtosis and detection
of outliers.
ii. Tools will be developed for parameter estimation of four
identified parameter estimation techniques (Method of
moments, method of maximum likelihood, Probability
weighted moments and L-moments approach) for Normal,
Lognormal, Pearson III, Log Pearson III, Gumbel and GEV
distributions.
iii. Tools for 4 (Chi-square, KS test, Cramer Von Mises and
ADC) Goodness of fit tests
iv. Interface will be developed for graphic representation of
best fit distribution and original series with confidence band

ES - x WATER RESOURCES
Ungauged/
Partially
gauged
Basins
Hydrometeo
rological
approach
(synthetic
Unit
Hydrograph)
i. Determination of response function for basins of size less
than 5000 km2 using Snyder’s method, Dimensionless unit
hydrograph and GIUH where concurrent rainfall and
discharge data are not available.
ii. Tools for implementation of CWC sub zonal reports.
iii. SRM model for snowmelt contribution
iv. HEC-RAS model for GLOF routing. Separate tool will be
developed for routing in steep slopes.
v. Tool for integrating GLOF with the intermediate catchment
runoff.
vi. For computation of flood hydrograph HEC-HMS model
have been identified
Regional
Flood
frequency
Approach
i. Tools to implement L-moment approach of RFFA analysis
ii. Tools for USGS method and Pooled curve method
iii. Tools for identification of region of influence (ROI) of the
Ungauged basins
Urban and
Agricultural
catchments
Hydrometeo
rological
Approach
i. Tool for Rational method for both urban and agricultural
catchments
ii. Kinematic wave model of HEC-HMS for Urban catchments
iii. SCS Curve number method of HEC-HMS
C. Sediment Rate Estimation (HDA-3)
Processes /Study areas Tools suggested
Estimation of
sedimentation yield
Reservoir Trap
Efficiency
Distribution of
Sedimentation in
Reservoirs
1. Use of actual observed data
(a) Development of sediment rating curves and flow
duration curves and their use for assessing
sediment yield/rates
(b) Use of reservoir resurvey data and trap efficiencies
for assessing sedimentation yield/rates
2. Development of GIS based regional relations for four
identified river systems based on observed data and for
use in ungauged areas.
3. Use of MWSWAT model
1. Revision of empirical Brune’s curves using reservoir
resurvey data from Indian reservoirs
1. Revision of empirical sedimentation distribution
procedures using reservoir resurvey data from Indain
reservoirs.
2. Use of one dimensional model like HEC-RAS

1-1 WATER RESOURCES
1. INTRODUCTION
1.1 BACKGROUND OF THE PROJECT
Environmentally, socially and financially sound management of water resources requires
long-term, reliable hydrologic information. Poor availability of comprehensive and good
quality hydrologic data leads to unsound planning and inadequate design and operation of
water resources projects. The National water policy emphasis that a well developed
information system, for water related data in its entirely, at the national / state level is a prime
requisite for resources planning. In this background, Ministry of Water Resources,
Government of India had earlier executed a World Bank assisted Hydrology Project – I (HP-
I) for improvement of hydrometeorological data collection procedures. HP-I was successfully
concluded in 2003 wherein 9 states and 6 central agencies including Central Water
Commission (CWC) participated.
The Hydrological Information System (HIS) created under Hydrology Project-I has the
provision for collection, collation, and storing of Hydro-meteorological data that includes
both Surface Water (SW), Ground Water (GW), Rainfall and Water Quality data. HP-I has
strengthened technical capacities of all participating agencies for moving towards long term
data management. This proved an important step in the direction of creating awareness about
the importance of this data asset among the participating states/ central agencies for proper
hydrological planning for water resources projects.
Government of India is now implementing a Hydrology Project – II (HP-II) as a sequel to
HP-I for building on and expanding development of a comprehensive Hydrological
Information System for improving access and use by various data user departments and others
in the society to boost efficient water resources planning and management. Activities under
HP-II have been planned both as horizontal and vertical extension of HP-I and as horizontal
extension, the project is being implemented in 13 states and 8 central agencies. As a part of
vertical extension, one of the activities proposed is “Development of Hydrological Design
Aids (HDAs)” with an aim to derive benefits from the works done under HP-I and to facilitate
the use of HIS created under HP-I.
The development of Hydrological Design Aids for use by all the States and Central Agencies
is being done through a consultancy project and Central Water Commission has appointed
M/s Consulting Engineering Services (India) Private Limited (CES) as the consultants for
Development of Hydrological Design Aids (Surface Water). The Contract No.:4/7/2009-
RDD/1 for consultant’s services for Development of Hydrological Design Aids (Surface
Water) between CWC and CES was signed on November 18, 2009 and the consultants started
the work from December 9, 2009.
1.2 NEED FOR DEVELOPMENT OF HDAS
Water Resources projects play a major role in the development of society, and for meeting the
increasing requirements of water, it is necessary that the hydraulic structures are planned after
intensive and extensive investigations and studies on various aspects of Hydrology.
Hydrological inputs form a basic ingredient for planning various water resources projects. As
the subject of hydrology is a database science, application of its knowledge to practical
problems requires a great deal of experience and sound judgement on the part of Hydrologists
and investigators. Proper hydrologic design of the projects results in better overall utilization
of available resources in general and needs more reliable estimates of available yield,
spillway capacity, and sedimentation etc. for better management and safety of hydraulic

1-2 WATER RESOURCES
structures. Since, a great deal of experience is required in solving practical problems the need
for acceptable design criteria’s/ guidelines/ aids have always been felt by practicing engineers
and hydrologists the world over including in India. Obviously the criteria’s and design
practices have evolved alongwith man’s experience, understanding of the principles of
hydrology and the practices being followed in different parts of the world. Centuries old local
water resources systems exist in the World and also in India, to meet the basic needs for
drinking water and irrigation. These works were not designed on any hydrological design
practices. As the science and man’s understanding progressed the practices for the
hydrological design of water resources projects improved and today the use of untested
empiricism has disappeared and has given way to rational hydrologic analysis. With the
developments in computer technology the techniques of hydrologic analysis have further
improved and procedures/guidelines have also suitably improved and updated.
Any hydrological study requires hydro-meteorological and hydrological data as a basic input
and the techniques and procedures which can be used depend to a great extent on the
availability of the information base. The techniques should therefore be suitably selected in
different data situations. At the same time the use of standardized hydrological design
practices in various organizations in the country is essential for uniformity in approach for
optimal planning of any Water Resources Project. It is therefore considered very important to
estimate the hydrological design parameters using standard design practices all over the
country and adopting state of the art technology to the extent it is possible keeping in view the
database that is available.
In the above background, the HDAs are being developed so as to overcome the limitations of
the current design practices and to standardize these practices for uniform use all over the
country. Under the project, the existing design practices are to be taken into consideration for
improvements in consultation with the states and CWC.
1.3 HYDROLOGICAL STUDIES REQUIRED FOR A WATER RESOURCES PROJECT
The terms of reference of the project not only require the development of HDAs but also
highlight the issue of integration of the design aids to produce a compact version and also to
have a provision for preparation of the hydrology chapter of a Detailed Project Report of a
water resources project. It is proposed to first prepare the configuration to produce a
hydrology report and the developed system should be an interactive system to prompt the user
to provide for certain information which will be necessary for producing the hydrology report.
The inputs to the report would have to be provided as basic inputs such as proposed project
features, general characteristics of the interest areas etc. and also the study results in a desired
format that will be obtained through the developed HDA tools. The hydrology report is to be
as per the latest guidelines issued by Ministry of Water Resources/ CWC.
The Ministry of Water Resources guidelines for preparation of Hydrology Chapter for a
detailed project report (DPR) indicate that information on following aspects should be
covered in the hydrology chapter of the DPR.
a) General Climate and Hydrology:
This should cover general information about the region, specific information about
drainage basin, command area, floods and drainage, river geometry, ground water
recharge, reservoir area, other water usage, navigation and information on available
meteorological and hydrological data supported by inventories. Specifications of formats
and details to be provided are highlighted in the guidelines.
b) Hydrological Data Requirement

1-3 WATER RESOURCES
This section shall discuss the type and extent of Hydrological Inputs required for the
proposed plan of development. The inputs required based on various developments are
stipulated in the guidelines.
c) Compilation and processing of Basic Hydrological Data
This part shall discuss the details of the specific data collected for the purpose. The basic/
processed hydrological data should be collected, compiled and discussed. Processing of
data, adjustment of records, consistency of data will be carried out and discussed. The
processed data shall be compiled and furnished keeping in view the hydrological inputs
required for the studies for development in question.
d) Preparation of Hydrologic Inputs for Simulation
This section shall cover the details and results of the analysis made for preparation of
various hydrologic inputs required for simulation studies to supplement the available data.
Studies completed for water inflows, lake evaporation, sedimentation studies to evaluate
effect of depletion of reservoirs’ useful capacity and potential evapotranspiration and
rainfall in command shall be discussed.
e) Preparation of Hydrological Inputs for studies other than Simulation
This part of the hydrology chapter shall include the studies and their results relating to
design flood, design flood level and tail water rating curve etc. Studies required for design
flood for safety of structures, flood storage and flood control works, design of drainage in
command area, diversion arrangements, levels for locating structures on river banks etc.
shall be discussed.
f) Simulation Studies
This section shall discuss the details of the simulation studies and the conclusions arrived
there from. The studies carried out for the alternative under consideration shall be
discussed in detail explaining all the factors and assumptions that have been made.
g) Effect of Project on Hydrologic Regime
The guidelines stipulate that this section shall include effect on low flows, peak flood,
total runoff and sediment flows in different reaches of the river due to the project.
The information on above aspects will have to be collected/ compiled through the data
inputs and studies carried out through the developed HDA tools so as to produce the
hydrology chapter of the DPR.
1.4 DESIGN PARAMETERS FOR DEVELOPMENT OF HDA
As indicated in para 1.3 above, the hydrology report for a proposed project should cover
general information, data requirements and processing, studies for preparation of hydrological
inputs, conclusions through the simulation studies and effect of the project on hydrologic
regime. It is seen that for any hydrological study the three main design parameters are:
a) Assessment of the resource potential for sizing a water resources development project
b) Estimation of design flood for the safety of any hydraulic structure
c) Estimation of sediment rate so as to assess the economic life of the project

1-4 WATER RESOURCES
In view of the above, the terms of reference of the consultancy assignment include, following
areas for developing HDA tools.
HDA 1: Assessment of Water Resources Potential – Availability/ Yield Assessment
HDA 2: Estimation of Design Flood; and
HDA 3: Sediment Rate Estimation
The resource assessment study is generally required to finalize water yield series as per the
requirements of a project. The finalization of yield series will deal with various data
availability situations and as per TOR, all methodologies on different time steps are to be
developed for different data availability scenarios. For the ungauged catchments regional
water availability models based on observed hydrological and meteorological data of few
selected catchments in the region will be developed. Regional models are to be developed for
minimum four identified river systems of the country.
The water resources potential assessment would end up with the assessment of virgin flows
and procedure for estimating the uncertainties or minimizing the uncertainties. These have to
be the integral part of this design aid.
For a snow covered catchment, the detail for flow segregation i.e. rainfed and snowfed
seasonal/ permanent snow line, rainfall and snowfall characteristics are to be defined. It
would be well compatible to deal different types of inhomogeneity present in a project
catchment. Snow melt estimation model under different data scenario is to be developed. The
design aid would also address the issue of data requirement and make references to prevalent
standard procedure for observations world wide and in India and suggestions on improvement
of data collection techniques. Various sub components in the yield series estimation would be
able to be used as stand alone wherever limited use is required.
Under HDA 2, design flood for different purposes is to be finalized based on all practices in
vogue including all standard approaches and data availability scenarios. The design flood
estimation will cover hydrometeorolocial approach, statistical approach and regional
approach. These approaches are used currently, as such, the basic objective is to develop
standard methods in the forms of easy to use monographs and/ computer software, through
critical reviews of the existing National and International practices. The method and
techniques that are currently being applied in India will be improved in conjunction with the
recommended methodologies used internationally as good practices, especially for ungauged
or partially gauged catchments. The HDA 2 to be developed will also consider cases of
unregulated and regulated natural streams having hydraulic structures upstream and
downstream of the considered location. The techniques in-built in HDA 2 would thus also
cater for integrated operation of reservoirs considering channel and reservoir routing as an
integral part. The TOR also include development of proper methodology for snow melt
contribution in case of snow fed catchments, methodology for estimation of GLOF (Glacier
Lake Outburst Flood) and hydrological planning of agricultural and urban catchments.
Under HDA 3 the basic objective is to determine the appropriate Dead Storage Elevation
(New Zero Elevation) for storage reservoirs for different time horizons as per BIS and CBI&P
guidelines. In case of gauged streams the collected/ observed sediment data will be used and
for ungauged catchments, the regional sediment curves (iso-erosion lines) are required to be
prepared for four different regions of the country based on observed information for rivers/
reservoirs.

1-5 WATER RESOURCES
1.5 SCOPE AND METHODOLOGY FOR THE CONSULTANCY
The hydrological design aids are proposed to be developed after due consideration and
assessment of the prevalent design practices recommended by CWC and other state water
resources departments, prevailing design practices in other parts of the World and their
relevance with respect to India both from techno-economic considerations and data
requirements and availability. The existing BIS and national guidelines available for
determination of various hydrological parameters are to be customized with modifications to
make them more rational and scientific to suit the requirements both in terms of degree of
accuracy and ease with which these can be used by water resources planners. The TOR of the
assignment require that a state of the Art Report (SAR) on each design aid is produced which
covers various National/ International practices, and recommends various practices that can
be used in Indian scenario. The SAR for all the three disciplines viz. water availability,
estimation of Design Floods and Sedimentation is to be prepared after review of practices
followed world wide and within India and has to cover the practices that are followed globally
with the information on data requirements for following such practices.
The practices followed in India by various organizations have been studied through the
available documents/ guidelines issued by CWC, BIS and other organizations. The practices
followed world wide have been studied by the team of experts of the consultant through
literature survey and various guidelines issued by important organizations working the world
over in the field of hydrology and available publications of International Organizations viz.
World Meteorological organizations and UNESCO etc. The outcome of these studies and
review of practices followed nationally/ internationally in the three disciplines of water
availability, estimation of design flood and sedimentation is elaborated in the following
chapters.

CHAPTER 2:
PREVALENT DESIGN CRITERIA AND
PRACTICES: THE INDIAN PERSPECTIVE

2.1-1 WATER RESOURCES
2. PREVALENT DESIGN CRITERIA AND PRACTICES: THE INDIAN
PERSPECTIVE
Hydrology Project-I was set up to improve the Hydrological Information System (HIS) in
India to arrive at comprehensive, easily accessible, and user-friendly databases covering all
aspects of the hydrological cycle. Such data are a prerequisite for a rational water resources
planning and management in a country facing already severe water shortages in the present,
not to mention in the near future. The HIS comprises the following components:
• A network of observational stations including sampling sites established to collect the
basic data for different meteorological, hydrological and geohydrological variables.
• A system of Water Quality Laboratories to analyze water samples on the concentration
of various water quality variables.
• A system of Data Processing Centres at various levels to enter the observed data on
magnetic media and to subsequently process the data to arrive at reliable information for
transfer to the database.
• Data Storage Centres, where both field and processed data sets are stored, i.e. processed
data for dissemination to the data users and field data for archiving original observation
and to permit inspection and revalidation at a future date if required.
The data collected range from surface water variables (including precipitation, stage,
discharge, and rating equations), through water quality variables and groundwater variables.
The data available through the HIS should enable more effective use of the tools developed
under Hydrology Project-II.
2.1 ASSESSMENT OF WATER RESOURCES POTENTIAL – AVAILABILITY / YIELD
ASSESSMENT
2.1.1 Approach
While planning projects, one was accustomed to deal with availability of water in terms of
annual totals, average or 75% dependable flows (annual volume). These concepts did not
address the availability of water at shorter intervals and at critical times which are crucial for
the planning, layout and design of hydraulic structures. With the upstream developments and
storage and complexity of systems – simulation of actual operation for satisfying various
demands is a necessity at the planning stage itself. For such simulation to be done, one has to
have a reasonable picture of anticipated post project conditions.
The objective of the current chapter is to briefly cover the design criteria/practices/guidelines
as stipulated by MOWR, CWC, NWDA, BIS, State Design offices, premier research
organisations and by various agencies working in the field of water availability and yield
studies in India. Under HP-I project, data processing software HYMOS was developed which
is being used in Central Water Commission besides nine states in India and other central
agencies. The existing practices discussed also include the various processing models which
are in HYMOS.
2.1.2 Hydrological data type and extent of hydrological inputs
With reference to Guidelines for preparation of Detailed Project Reports of Irrigation and
Multipurpose projects, Government of India, Ministry of Water Resources (MOWR) /
Guidelines for Detailed Project Report by Central Water Commission (CWC), the type and
extent of hydrological inputs for the proposed plan of development depends on the type of

structure and on the contemplated use of water at storage space. The classification of
alternative plans based on above inputs are indicated in Annex- 2.1.
2.1.3 Compilation and Hydrological Data Processing
2.1.3.1 Filling of short data gaps
a) As per the Guidelines for preparation of Detailed Project Reports of Irrigation and
Multipurpose projects, MWR / Guidelines for Detailed Project Report by CWC, the
techniques which are proposed for gap filling are as follows :
• Random choice from values observed for that period
• Interpolation from adjoining values by plotting a smooth hydrograph
• Using average production with normals for the adjoining stations
• Double Mass curve techniques
• Correlation with adjoining stations either of the same/different hydrologic element
• Auto correlation with earlier period at the same station
• Any other
b) In the HYMOS software, following methods are available for filling of short data gaps.
i. Linear interpolation,
ii. Block type filling-in
iii. Series relation
iv. Spatial interpolation.
i. Linear interpolation
Linear interpolation is a method of curve fitting using linear polynomials. It is a simplest form
of interpolation. In a number of cases gaps in series can well be filled-in by linear
interpolation between the last value before the gap and the first one after, provided that the
distance over which interpolation takes place is not too large.
If the two known points are given by the coordinates and , the linear
interpolant is the straight line between these points. For a value x in the interval , the
value y along the straight line is given from the equation:
(1)
Solving this equation for y, which is the unknown value at x, gives
(2)
which is the formula for linear interpolation in the interval
ii. Block type filling – in
Filling-in data according to the block-type comprises the replacement of missing data by the
last non-missing value before any gap.
iii. Series relation
Relation/regression equations can be used to fill-in missing data, provided that the standard
error in the fit is small. Polynomial / simple linear / exponential equations can be used to fill-
in missing data.
Regression models involve the following variables:
• The unknown parameters denoted as β; this may be a scalar or a vector of length k.
• The independent variables, X.
• The dependent variable, Y.A regression model relates Y to a function of X and β.

The approximation is usually formalized as E(Y | X) = f(X, β). To carry out regression
analysis, the form of the function f must be specified (polynomial/linear/exponential).
iv. Spatial interpolation
The spatial interpolation technique is applicable to quality and quantity parameters with a
spatial character, like rainfall, temperature, evaporation, etc., but sampled at a number of
stations (point measurements). Missing data at a test station are estimated by weighted
averages of observations at neighbouring stations. The weights are inversely proportional with
some power of the distance between the test station and the neighbour stations. The
requirements of this method are:
• series with selected data type and the same interval as the one under investigation should
be available;
• the distance between the test station and a neighbor should be less than a specified
maximum correlation distance Rmax (km);
Estimation of point rainfall
The point estimate for the base station u at a given point x based on the observations uk = u(xk)
for k = 0,1,...,N at N neighbour stations for the same time interval is given by equation:
(3)
Where,
(4)
x denotes an interpolated (arbitrary) point, xk is an interpolating (known) point, d is a given
distance from the known point xk to the unknown point x, N is the total number of known
points used in interpolation and p is a positive real number, called the power parameter.
c) As stipulated in Guide to Hydrological Practices, WMO No. 168, “judgement is required in
deciding how much missing data should be estimated. If too few gaps are estimated, then
large quantities of nearly complete records may be ignored. If too many data are estimated,
then the aggregate information content may be diluted by interpretation. It is rarely justified
to estimate more than five or 10 per cent of a record.”
2.1.3.2 Adjustment of records
a) The adjustment of flows to natural and virgin conditions for historical use in the upper
reaches requires withdrawal data, reservoir operation data and irrigation statistics. Where
adjustments due to upstream storage are made, storage changes and evaporation losses are to
be accounted for. Apart from adding upstream withdrawals, return flows have to be
subtracted. (Reference: Guidelines for preparation of Detailed Project Reports of Irrigation
and Multipurpose projects, MWR / Guidelines for Detailed Project Report by CWC)
i. The adjustment of the observed flows/sediment data may not be necessary if
• Utilisation by upstream projects has been same throughout the period of observation of
flows and sediment.
• The pattern of usage has not changed appreciably or with a definite need
ii. Adjustment with the flow and sediment records shall be required in other cases e.g. where
appreciable changes in land use have taken place.
iii. Adjustment of flood and low flows to remove the effect of upstream regulation may be
required where this is appreciable.

b) Natural (virgin) flow in the river basin is reckoned as water resource of a basin. The mean
flow of a basin is normally obtained on pro-rata basis from the average annual flow at the
terminal site for the desired period. For an overall assessment of water resource of a basin,
data of runoff (i.e., discharge or flows) for about 20 years may be considered adequate,
whereas for detailed project involving planning data for a much longer period is needed. In
case observed data for the entire period needed are not available, the gap is filled in by
interpolation or extrapolation, as needed, based on rainfall-runoff equations. (Reference:
Report of the working Group on Water Availability for use, National Commission for
Integrated Water Resources Development Plan, MWR, India, September, 1999))
Water resources have already been developed and utilized to a considerable extent in the river
basins through construction of major or medium storage dams and development of
hydropower, irrigation and other water supply systems. A large number of diversion schemes
and pumped schemes have also been in operation. Assessment of natural flow has become
complex in view of the upstream utilization, reservoir storages, regenerated flows and return
flows, etc. The natural flow at the location of any site is total of observed flow, upstream
utilization for irrigation, domestic and industrial uses both from surface and ground water
sources, increase in storage of reservoirs and evaporation losses in reservoirs. Return flows
from different uses from surface and ground water sources are deducted.
The following equation describes the computation of natural flow from observed runoff,
utilizations for different uses, effect of storage, evaporation loss and return flows from
different uses.
R(N) = R(O) + R(IR) + R(D) + R(GW) – R(RI) – R(RD)- R(RG) + S + E (5)
Where
R(N) – Natural flow,
R(O) – Observed flow,
R(IR) – Withdrawal for irrigation
R(D)- Withdrawal for domestic and industrial requirements
R(GW) – Groundwater withdrawal
S- Increase in storage of the reservoirs in the basin,
E-Net evaporation from the reservoirs
R(RI)- Return flow from irrigated areas,
R(RD)- Return flow from domestic and industrial withdrawal,
R(RG) – Return flow from ground water withdrawal.
The data on abstractions for irrigation are generally obtained from the records maintained by
irrigation project authorities. Where such records are not available, the abstractions are
estimated from information on area irrigated and the delta.
Data on withdrawals for the purposes of domestic and industrial uses are not generally
available. Hence, only rough estimates are made on the basis of population and available
information on per capita for domestic use and industrial uses.
The total ground water draft for the country as a whole is estimated by Central Ground Water
Board. Ground water utilization for different years is estimated based on ground water draft.
For some of the existing reservoirs, records of evaporation losses are maintained by project
authorities. Where such data are available, they are used to estimate evaporation losses. In
case of projects, where such data are not available, generally 20 percent of annual utilization
is taken as evaporation loss.
Return flows from irrigation use are assumed at 10 to 20 percent of the water diverted from
the reservoir for irrigation. In case of localized use of ground water for irrigation, the return

flow is assumed to be negligible. The return flows from domestic and industrial uses either
from ground water or surface water source are assumed to be 70 to 80 percent.
2.1.3.3 Consistency of data
a). The methods indicated for checking data consistency as per Guidelines for preparation of
DPR of Irrigation and Multipurpose projects, Government of India, MWR / Guidelines for
Detailed Project Report CWC are:
Internal consistency
The check can be done by stage discharge relationship for different periods. Large variations,
if any, shall be investigated, corrected and explained suitably.
External consistency
The consistency of observed data shall be discussed with reference to the rainfall in the
project catchment and observed data in adjacent locations / basins. The consistency can be
checked by
• Comparing monthly and annual rainfall with corresponding runoff
• Comparing average annual specific flow with corresponding figures at other sites of
the same river or adjacent basin
• By comparing the hydrograph of daily discharge at the control point with adjacent
sites
• By use of double mass curve techniques
Details of the study made for various hydrological observations at control points and sites
maintained by CWC/states and other agencies shall be summarised and presented as:
• Average annual/monthly/seasonal flow volumes expressed as depth of water over
drainage area
• Average maximum/minimum discharge (cumec/sq km for concurrent period)
b) The methods discussed in Hydrological aspects in Project Planning and Preparation of
Detailed Project Report by Training Directorate, Central Water Commission are:
Internal consistency
• Absolute limits
• Rate of change
• Graphical plot
• Time series analysis
External consistency
• Comparison plots
• Residual series
• Double mass curve
• Rainfall-Runoff comparison
• Regression Technique
c) Some of the methods for consistency tests for validation of series available in HYMOS are :
Listing of series Table of time series, with marking of the origin of the series, (i.e.
original, completed or corrected) or the quality of the series (i.e.
reliable, doubtful or unreliable).
Screening of series Table of time series, with basic statistics and marking of outliers.
Comparison of series For pairs of series all elements are shown at the times they differ.
Tabulation of series Column-wise presentation of up to 6 series side by side.
Less/greater than Only data less than or greater than a specified value are tabulated.

Same readings Table of time series, with marking if consecutive value is same for
specified number of time steps.
The Time series graphs options are meant for data validation purposes and/or reporting. This
option include graphs of:
• Time series, i.e. plot of an infinite number of series for the same time period, plotted
as lines and/or as bars.
• Residual series, i.e. a time series plotted relative to its mean as a function of time.
• Residual mass curves, i.e. a time series plot of accumulated differences from the
mean.
• Moving averages, i.e. plot of time series with its moving average over a specified
period.
• Water balances, i.e. plot of a computed sum or difference of time series.
• Data Availability, i.e. plot of time periods where data is non-missing.
• Derivative, i.e. a time series plot of the difference between each time step.
• Log-Log, i.e. a plot of two series on a double logarithmic scale.
• Combined series, i.e. a time series plot of a series with the stage discharge data of the
same time period.
• Series with limits, i.e. a time series plot of a series with its maximum and minimum
limits.
The consistency tests with respect to average flow series for yield study are :
Double Mass Curve
Arithmetic serial correlation coefficient: a test for serial correlation;
Wilcoxon-Mann-Whitney U-test
Wilcoxon Wtest: a test on difference in the mean between two series
Student t-test: a test on difference in the mean between two series
Linear trend test: a test on significance of linear trend by statistical inference on slope
of trend line;
Some of the above mentioned methods which are commonly used for consistency tests are
described in Annex 2.2.
2.1.3.4 Data Extension
The study and methodology used (Reference : Guidelines for preparation of DPR’s of
Irrigation and Multipurpose projects, Government of India, MWR / Guidelines for DPR by
CWC) for extending short term runoff series to desired length of time are as follows :
a. Co-relating runoff data with concurrent data on rainfall of long term stations in the
same catchment or data of runoff of adjacent long term stations and applying these
co-relations developed to past data of long-term stations of rainfall-runoff
b. Such correlation shall be developed for each time unit selected.
The following points are required to be considered
• Rainfall-runoff correlation may not be feasible or necessary for non-monsoon period
• Overall acceptability of correlation shall be checked
• Random components may be considered where corrections are not very strong.
Based on the information / inputs required, and having assessed the basic data availability, the
hydrologist has to use various techniques to extend/generate long term flow sequence for
proper evaluation of water availability and project planning. The observed data at a desired
location is commonly not available and as such suitable techniques to extend / generate long
term flow sequence is generally used in India. The methodology/models used for this purpose
could be (a) Data Extension (b) Information transfer from one catchment to another (c)

Transfer of model coupled with data extension and (d) Synthetic generation of data. In India
Rainfall-Runoff or Runoff-Runoff correlations of different forms are commonly adopted.
2.1.3.5 Data generation
Two approaches are recommended for data generation as per Guidelines for preparation of
DPR’s of Irrigation and Multipurpose projects, Government of India, MWR / Guidelines for
DPR by CWC which are :
Stochastic modelling – Study of Trends and cycles in the data, justification and necessity of
removal of trend and cycle, auto-correlation and possibility of smoothening auto-correlation
values from regional studies, frequency distribution of random error component, generation of
random numbers.
Conceptual Modelling
2.1.4 Water Availability Assessment
Water availability estimation is acknowledged as a central governing factor in determining the
size of a project. Various approaches have been formulated by different agencies for
estimation on different time scale which have been compiled in the present section.
The procedure / methodology adopted for working out water balance covers type of soil,
estimation of yield, ground water potential, water requirement, regeneration etc. The
methodology stated in yield estimation as per Guideline for the preparation of preliminary
Water Balance Reports, NWDA, GOI has been presented as Annex 2.3
The purpose of water availability assessment of any type of hydroelectric projects is to
compute streamflow series over a period of time of about 20-25 years. This flow series is
utilised to fix the installed capacity of power house and to evaluate energy generation. The
methodology for computing flow series would depend upon the type and extent of available
river flow data. The hydrologic techniques to be adopted for inflow studies would cater to the
following data situations.
a) Long term measurement of river flows, say 20-25 years
b) Short-term measured river flows (say 5-10 years) and long term rainfall records in the
relevant catchment
c) Short term measured river flows but no records of rainfalls in the relevant catchment
under two situations :
• Data available for a period of 5-10 years
• Data collected for a minimum period of two lean and one flood season
The methodologies under the above data scenarios as outlined in Manual on Planning and
Design of Small Hydroelectric Schemes, CBIP, India are given in Annex 2.4 .
Finalisation of yield series at a given location in a catchment depends on many factors. Some
of these factors are interdependent. The most rational approach in finalization of flow series
for a water resource project is based on site specific data. In such a case, final yield series can
be recommended after validation and processing of flow data. But this is a rare case and most
of time, flow data upstream or downstream are used. However, due consideration should be
given regarding the contribution of intervening catchment in case flows of nearby G&D site
is being utilized. The methodologies of water availability assessment as per Hydrological
Aspects in Project Planning and Preparation of DPR, Training Directorate, CWC, MWR,
GOI are indicated in Annex 2.5.

Provision of Environmental Flows
National Water Policy (MOWR 2002) ranks “ecology” as the fourth item in the list of
priorities for water-allocation. As the progressive degradation of the water environment
became evident, environmental concerns have started to gain strength. This is, perhaps, where
and when the term ‘minimum flow’ originated from. Minimum flow was understood as a
flow, which is needed (to be released) downstream from the dams for environmental
maintenance.
The issue of minimum flow was highlighted in a judgment of the Supreme Court of India,
which in 1999 directed the government to ensure a minimum flow of 10 cubic meters per
second (m3/s) in the Yamuna River as it flows through New Delhi for improving its water
quality. Since then the minimum flow requirement in rivers has been discussed at several
forums (but primarily in the context of water quality). In 2001, the Government of India
constituted the Water Quality Assessment Authority (WQAA) which in turn constituted, in
2003, a Working Group (WG) to advise the WQAA on ‘minimum flows in rivers to conserve
the ecosystem’. Despite the continuous use of the term ‘minimum flow’, the committee made
the following recommendations;
Himalayan Rivers
1. minimum flow to be not less than 2.5% of 75% dependable Annual flow expressed in cubic
meters per second.
2. one flushing flow during monsoon with a peak not less than 250% of 75% dependable annual
flow expressed in cubic meters per second.
Other Rivers
1. Minimum flow in any ten daily period to be not less than observed ten daily flow with 99%
exceedance. Where ten daily flow data is not available this may be taken as 0.5% of 75%
dependable flow expressed in cubic meters per second.
2. One flushing flow during monsoon with a peak not less than 600% of 75% dependable flow
expressed in cubic meters per second.
The committee also noted that this recommendation will have to be reviewed in collaboration
with International Water Management Institute (IWMI) and other world bodies. The IWMI
findings are documented in Report no 107 , where in a method to compute Environmental
flows is proposed and these flows are computed for various ecological conditions for various
Indian rivers. Further a Global Environmental Flow Calculator (GEFC) is now available fro
IWMI and can be used for computing environmental flows.
2.1.5 Continuous simulation Models / related data processing model developed in India
2.1.5.1 HYPRO package
HYPRO package has been developed for data storage, processing and retrieval system for
hydrological data by National Institute of Hydrology (Reference : Report No UM-47 National
Institute of Hydrology,1995-96). The software has been proposed to overcome inefficiencies
and consequent difficulties of multi file organization in data handling. Hydrological analysis
which can be performed are as follows.
(i) Statistical summary (viz. mean, standard deviation, skewness, kurtosis, series correlation
coefficient an maximum and minimum of data series)
(ii) Time series analysis (viz. Autoregressive model for simple case of stream flow, Moving
average model, Auto Regressive-Moving Average method for mixed behavior of stream flow
(combination of precipitation and groundwater flow), Auto covariance and Auto correlation
coefficient model) Finally an iterative approach of model building has been described (viz.
Model identification, Parameter estimation Diagnostic Checking).

(iii) Frequency analysis (fitting various probability distributions to hydrological data if stochastic
component of the time series is independent. Finally, outlier/inlier analysis, check for
persistence and plotting position has also been done.)
2.1.5.2 Water Yield Model (WYM)
The system Engineering Unit of Central Water Commission has developed a Water Yield
Model as an aid to Water Resources Planning and water management decisions. This is a
lumped parameter continuous model for simulating runoff volumes on monthly basis. A
comprehensive planning by system analysis involving integration of various reservoir
operation require monthly flows at all key reservoir sites. Further, the location of raingauges
matching the pattern of rainfall spatial variability from month to month is the limiting factor
for the size of the catchment that can be modelled by their lumped approach. Due to lumping
of rainfall inputs over a month, the sensitiveness of the mechanism infiltration, percolation,
overland flow, interflow, baseflow and the ground water storage are reduced on account of
their lumping over a month.
Therefore, modelling of three main constituents namely, evapotranspiration, surface runoff
and base flow by appropriate mathematical formulations is considered to be adequate rather
than to model all the processes involved in the land phase of the hydrologic cycle. The model
structure has been described in Annex 2.6.
The model has been used in several catchments in India successfully.
2.1.6 Rainfall-Runoff Models developed for some regions in India :
Strange evolved some ratios between rainfall and runoff based on data of Maharashta, India.
He accounted for the geological conditions of the catchment as good, average and bad, while
surface condition as dry, damp and wet prior to rain. The values recommended by him are
given in Table 2.1
Table 2.1 Rainfall runoff ratios for different surface conditions
Daily
rainfall
(mm)
Runoff percentage and yield when the original stage of ground is
Dry Damp Wet
Percentage Yield (mm) Percentage Yield (mm) Percentage Yield (mm)
5 - - 4 0.2 7 0.35
10 1 0.10 5 0.5 10 1.00
20 2 0.40 9 1.8 15 3.00
25 3 0.75 11 2.75 18 4.50
30 4 1.20 13 3.9 20 6.00
40 7 2.80 18 7.2 28 11.20
50 10 5.00 22 11.0 34 17.00
60 14 8.46 28 16.8 41 24.60
70 18 12.61 33 25.10 48 33.60
75 20 15.00 37 27.75 52 41.25
80 22 17.6 39 31.20 55 44.00
90 25 22.5 44 39.60 62 55.80
100 30 30.00 50 50.00 70 70.00
Note : for good or bad catchment add or deduct up to 25 % yield.
Inglis and De Souza’s Formula (1946) :
Inglis and De Souza used data from 53 stream gauging sites in Western India. He studied
catchments in western ghats and plains of Maharashtra, India and gave the following
relationships

For ghat areas
R = 0.85 P – 30.5 (6)
For Plains
R = 254
)8.17( PP −
(7)
Where R = runoff (cm)
P = precipitation (cm)
Binnie’s percentages (1872) (taken from Hydrology Part III 1978)
Sir Alexander Binnie measured the runoff from a small catchment (16 km2) near Nagpur
during 1869 and 1872, developed curves of cumulative runoff against cumulative rainfall (for
annual rainfall of 500 to 800 mm) and established percentages of runoff from rainfall. These
percentages have been used in the Madhya Pradesh and Vidarbha regions of Maharashtra for
the estimation of mean annual flow.
Khosla (1949), developed a relationship for monthly runoff:
Rm = Pm – Lm (8)
Lm = 0.48 Tm for Tm > 4.5 0
C (9)
where: Rm = Monthly runoff in cm , Pm = Monthly rainfall in centimeters (cm), Lm = Monthly
losses in centimeters, Tm = Mean monthly temperature of the catchment in o
C. He supplied
provisional values of losses for different temperatures. Annual runoff can be estimated as a
sum of monthly values. Khosla’s formula is indirectly based on the water-balance concept and
the mean monthly temperature is used to reflect the losses due to evapotranspiration. The
formula has been used on a number of catchments in India and is found to give fairly good
results for the annual yield for use in preliminary studies.
UP Irrigation Research Institute (1960) formulae:
Uttar Pradesh Irrigation Research Institute, Roorkee, has developed the following
relationships between runoff and precipitation:
Himalayan rivers
Ganga Basin at Hardwar (23,400 km2
) R = 5.45 P0.60
(10)
Yamuna Basin at Tajewala (11,150 km2
) R = 0.354 P0.11
(11)
Sharda Basin at Banbassa (14,960 sq.km) R = 2.7 P0.80
(12)
Bundelkhand area rivers (in Uttar Pradesh State)
Garai Basin at Husainpur (290 km2) R = 0.58 P −2.8 (13)
Ghori Basin at Ghori (36 km2) R = P −62.3 (14)
Ghaghar Basin at Dhandraul (285 km2) R = 0.38P (15)
Sukhra Basin at Sukhra (15 km2) R = 0.47 P −2.8 (16)
Karamnasa Basin at Silhat (518 km2) R = 0.49 P (17)
where: R is runoff in centimeters and P is rainfall in centimeters.
UPID’s formula.
The Uttar Pradesh Irrigation Department (UPID) developed the following correlation between
rainfall and runoff for Rihand River:
R = P −1.17 P 0.86
(18)
Where: R and P are runoff and rainfall in centimeters.

A Rational relationship was developed by Narsimaiya et. Al. (!991) to derive rainfall –runoff
relationship for Subernarekha river basin taking into account antecedent rainfall effect, land
use, elevation and catchment slope.
Kothyari (1995) used data from 31 non-snow fed catchments in India with areas less than
1,515 km2 in the Indian states of Uttar Pradesh, Madhya Pradesh, Bihar, Rajasthan, West
Bengal and Tamil Nadu – to develop a simple method for the estimation of monthly runoff
for the monsoon months of June to October in the following form:
{ }[ ] )()(/)1()1(1)(1)()( 1)(
IPIPIPIKIKIKIR IN
−−−+= −
(19)
where: R(I) = monthly runoff during the Ith month, P(I) = monthly areal rainfall during the Ith
month, K(I) and n(I) are parameters for the Ith month with K(I)<1.0 and n(I)>1.0. The values
of the exponent n(I) were found to vary significantly in Damodar (Bihar), Barakar (Bihar),
Mayurakshi (West Bengal), Chambal (Madhya Pradesh), Lower Bhawani (Tamil Nadu) and
Ram Ganga River (Uttar Pradesh) during any one month and the coefficient K was found to
be related to T, FA and A according to equation given below as it represents the loss from the
total rainfall.
K = 260.9 T-2.02
FA
-0.05
A0.05
where: T is temperature in o
C, A is the catchment area in km2
and FA is the percentage of
forest area. The values computed by the model were then compared with the corresponding
observed values of runoff. This comparison revealed that the proposed method produces
results with an error less than 25% for 90% of the data points. However, an error of less than
50% resulted for the arid catchments from the Chambal Basin (Madhya Pradesh).
References
Inglis, C. C and De souza, “ A critical study of runoff and floods of catchment of the Bombay
Presidency with a short note on loss from lakes by evaporation”, Bombay PWD Technical
paper No. 30 (1930).
Dhir, R. D., P.R. Ahuja and K. C. Majumdar, “ A study on the success of reservoir based on
actual and estimated runoff”, Paper presented at the Research Session of Central Board of
Irrigation and Power, India (1958).
Narasimaiya, M. K. , Upadhyay A, “Computer Applicartion in Hydrology for Runoff
Determination – A Rational Method”, National Seminar on use of Computers in Hydrology &
Water Resources, CWC, 1991.
Jha R., Smakhtin V., “A review of methods for H/ydrological estimation at ungauged sites in
India”, IWMI Working Paper 130
UPIRI (Uttar Pradesh Irrigation Research Institute). 1960. Rainfall-runoff studies for a few
Himalayan and Bundelkhand catchments of Uttar Pradesh TM 30-RR (HY-31).
Inglis, C. C. and de Souza (1946). Meanders and their bearing in river training. Maritime
Paper No. 7, Institution of Civil Engineers, London.
Khosla, A. E. 1949. Analysis and utilization of data for the appraisal of water resources, The
Central Board of Irrigation and Power Journal.
Kothyari, U. C. 1995. Estimation of Monthly Runoff from Small Catchments in India.
Journal of Hydrological Sciences 40: 533-541.

2.1.7 Design Practices adopted by State Government for yield estimation in India,
Based on the reports and informations collected from states, it has been observed that the
yield estimation procedures adopted by various states are in confirmation with the Central
Water Commission and Indian Standards guidelines, in general under the constraints of data
availability.
Maharashtra state, Water Resource Department has reported that the yield assessment are
based on 1980 Working Group Recommendations, GOI. PWD Handbook, Government of
Maharashtra, Chapter 19 on Hydrology describes the rainfall, evaporation, transpiration,
Evapotanspiration and discharge measurement related methodologies, regression and
correlation analysis techniques. Data Processing Centre at Nashik are using state of the Art
methods through HYMOS, SWDES and WISDOM in data processing. The procedure of
water availability study involves utilisation of observed gauge discharge / Tank gauge data.
Standard procedures are used in computing basin average rainfall. Naturalization of flow is
made by Water Balance method considering upstream utilizations. The yield series is
developed from rainfall-runoff correlation.
The practices followed by Gujarat Water Resource Department in water availability involve
the following procedures
- Collection and checking of data
- Rainfall – Interpolation and adjustment of missing data
- Naturalization considering upstream utilizations
- Developing regression model for monsoon periods and non monsoon period
- Net yield calculation considering all upstream existing and planned utilizations.
In Himachal Pradesh, small hydroelectric projects as run of the river schemes are developed
which are based on the existing gauge data. In the presence of flow informations available in
the same or nearby homogenous basins, catchment area proportioning method is used. In the
absence of any coefficient based on catchment characteristics is evolved.
The procedure and Criteria followed by State Govt of Rajasthan are:
When the observed runoff data are not available, the yield is computed using Strange’s table.
The Strange’s table gives runoff for good, average and bad catchments and surface conditions
ciz dry, damp and wet prior to the rain.
When the observed runoff data along with the observed rainfall of any nearest G & D site is
available the yield is computed using regression analysis. A relation between observed
monthly rainfall and observed monthly runoff for the G & D site is generated and it is
transposed over the catchment of the project using the rainfall-runoff relationship between
observed rainfall of G & D site and observed rainfall for the project.
The Procedure and Criteria followed by State Govt of West Bengal are :
For extension of streamflow records, the following methods are used:
1. Double Mass curve method
2. Correlation with catchment areas
3. Regression analysis
4. Index-station method
5. Langbeins log deviation method.
For yield assessment of Damodar river basin (19 900 km2
) Dhir, Ahuja and Majumdar’s
Relation is adopted :
R = 13 400P – 5.75 x 105
Where R = Runoff (cm) and P = Precipitation (cm)

2.1.8 State-of-the-Art technology developed in various parts of the world and applied in
Indian catchments by various Premier Research Institutes of India
Several flow simulation models available internationally were applied in Indian catchments
by premier research organisations. The results and conclusions are briefly mentioned as :
The ‘Systeme Hydrologique Europeen’ modeling system has been applied to six
subcatchments covering about 15000 km2
of the Narmada basin in Madhya Pradesh, Central
India by J.C.Refsgaard, S. M. Seth, J.C.Bathurst, M. Erlich, B. Storm, G. H. Jorgensen and S.
Chandra (1992) (Refer Appendix D8 for model description and Annex 2.7 for details)
From the application and results obtained from six catchments in India, the authors conclude
that
SHE is able to reproduce the rainfall-runoff process and give a physically reasonable
representation of intermediate hydrological processes for characteristic monsoon
environment.
The data requirement of SHE although high, can be collected from different agencies and
a supplement of field data is desirable for an improved assessment of hydrological
regimes.
Considering the generalized structure and process description, SHE is recommended as
the optical tool only for some types of hydrological problems like a) Rainfall-runoff
modeling for extension of streamflow records from long historical rainfall series, simpler
models will be equally accurate and easier to apply. SHE is therefore not generally
recommended for tackling problems related to prediction of discharge from a catchment.
b) For issues related to effects of man’s activities, land use changes, interaction between
surface and ground water, water management in command area, effects of climate change
etc., SHE is well suited. c) SHE is well suited for water quality and soil erosion modeling.
-----------------------------------------------------------------------------------------------------------------
A Modified SCS-CN Based Hydrologic Model was applied by Dr. S. K. Mishra (Reference :
TR(BR) – 2 / 1999-2000). The model formulation is based on conversion of precipitation to
rainfall excess using SCS-CN method and its routing by single linear reservoir and linear
regression techniques with following assumptions :
• The variation of parameter S was governed by antecedent moisture condition.
• The baseflow was assumed to be a fraction of the infiltration amount.
• The baseflow was routed to the outflow of the basin using lag and route method.
• The parameters of the model was computed using non-linear Marquardt algorithm.
The model was applied to daily rainfall-runoff data of Hemvati catchment and upper
Ramganga catchment of 600 sq km and 3134 sq km area respectively. By study under various
cases of calibration and validation data pattern , the author has concluded that data length of
higher magnitude is required for stability of model parameters. (Refer Annex 2.8 for details)
-----------------------------------------------------------------------------------------------------------------
The modified SCS-CN method has been used for continous modeling for volume of surface
runoff for small agriculture watersheds in Ramganga and Hemvati catchments of India by
S.K.Mishra, V. P. Singh (1999). The modifies version assumes that the initial abstraction
component accounts for surface storage, interception and infiltration before runoff begins.
Therefore, it can take any value from 0 to ∞. The authors concluded that the modified version
of SCS-CN method is more accurate than the existing SCS-CN method.(Refer Annex 2.8 for
details)
-----------------------------------------------------------------------------------------------------------------
A time distributed spatially lumped SCS-CN based runoff method is developed and applied to
seventeen events of Jhandoo Nala watershed in Himalaya affected by mining activities, and

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