Preparation of Dpr - Hydrological studies

Prpeparation Of DPR - HydPrpeparation Of DPR - Hydrologyrology

PREPARATION OF DPRPREPARATION OF DPR

HYDROLOGYHYDROLOGYN. K. MathurN. K. Mathur

Director CWCDirector CWCHydrology (NE)Hydrology (NE)


Base DocumentsBase Documents

Guidelines for preparation of Detailed Project Guidelines for preparation of Detailed Project Report of Irrigation and Multipurpose Projects by Report of Irrigation and Multipurpose Projects by Working Group of the then Ministry of Irrigation Working Group of the then Ministry of Irrigation (CWC) (CWC) (read with Guidelines for Submission, Appraisal (read with Guidelines for Submission, Appraisal and Clearance of Irrigation and Multipurpose and Clearance of Irrigation and Multipurpose Projects (CWC) )Projects (CWC) )Guidelines for formulation of detailed project Guidelines for formulation of detailed project reports for hydro electric schemes, their reports for hydro electric schemes, their acceptance and examination for concurrence acceptance and examination for concurrence (CEA-2007)(CEA-2007)


Related Technical DocumentsRelated Technical DocumentsGuidelines for preparation of project estimates for major irrigation and Guidelines for preparation of project estimates for major irrigation and multipurpose project” issued by CWCmultipurpose project” issued by CWCGuidelines for “Investigation of major irrigation and hydro-electric projects” Guidelines for “Investigation of major irrigation and hydro-electric projects” issued by CWCissued by CWCManual on estimation of Design flood (CWC)Manual on estimation of Design flood (CWC)CBIP – Technical Report No.19 “Life of Reservoir (1977) CBIP 89CBIP – Technical Report No.19 “Life of Reservoir (1977) CBIP 89IS 4890 : Method for measurement of suspended sediment in open riversIS 4890 : Method for measurement of suspended sediment in open riversIS 4186 : Guide for preparation of project report for river valley projects.IS 4186 : Guide for preparation of project report for river valley projects.IS 4877 : Guide for preparation of Estimate for River Valley ProjectsIS 4877 : Guide for preparation of Estimate for River Valley ProjectsIS 5477 : Methods for fixing the capacities of reservoirs. IS 5477 : Methods for fixing the capacities of reservoirs.

(Part 1-4)(Part 1-4)IS 7323 : Method for determining evaporation from reservoirs.IS 7323 : Method for determining evaporation from reservoirs. IS 7323 : Guidelines for operation of reservoirs.IS 7323 : Guidelines for operation of reservoirs. IS 13028 : Guidelines for overall planning of river basin.IS 13028 : Guidelines for overall planning of river basin.


HYDROLOGICAL INPUTS (for HYDROLOGICAL INPUTS (for Type of Projects)Type of Projects)

StorageStorage– Diversion without PondageDiversion without Pondage– Diversion with PondageDiversion with Pondage– Within Year storageWithin Year storage– Over the Year storageOver the Year storage

PurposePurpose– IrrigationIrrigation– HydropowerHydropower– Water Supply and IndustrialWater Supply and Industrial– Flood ControlFlood Control– Others (Navigation, Salinity Control, WQ Control, Draingae, Others (Navigation, Salinity Control, WQ Control, Draingae,

Recharge etc)Recharge etc)


HYDROLOGICAL INPUTSHYDROLOGICAL INPUTS

For Simulation StudiesFor Simulation Studies– Water Availability Studies (Inflow series)Water Availability Studies (Inflow series)– Lake evaporationLake evaporation– PET and RFPET and RF– Sediment Inflows and NZE Revised ACSediment Inflows and NZE Revised AC– Water QualityWater Quality– Low Flow, Ground water recharge etcLow Flow, Ground water recharge etc


HYDROLOGICAL INPUTSHYDROLOGICAL INPUTS

Design Flood Studies and levels forDesign Flood Studies and levels for– Safety of StructureSafety of Structure– Flood Control works Flood Control works – Drainage worksDrainage works– Diversion worksDiversion works– Locating structures and outlets in vicinity of Locating structures and outlets in vicinity of

river bank/ reservoirriver bank/ reservoir– Tail water rating curveTail water rating curve


Hydrological StudiesHydrological Studies

Water Resources AssessmentWater Resources Assessment

Design flood for structural safety and Design flood for structural safety and Diversion during constructionDiversion during construction

Sediment load in the stream and life of Sediment load in the stream and life of reservoirreservoir


DATA REQUIREMENTDATA REQUIREMENT

River GaugeRiver Gauge 10 yrs10 yrs Three daily (des- Hourly)Three daily (des- Hourly) DailyDaily

River Flow River Flow dischdisch

10 yrs10 yrs 20-30 during High flow 20-30 during High flow (des –daily)(des –daily)

WeeklyWeekly

Sediment flow Sediment flow and grain size and grain size compositioncomposition

3 yrs3 yrs Along with disch obsAlong with disch obs dittoditto

Water quality Water quality and salinityand salinity

3 yrs3 yrs Once in a month with Once in a month with dischdisch

More More frequfrequ

Rainfall ORG Rainfall ORG and SRRGand SRRG

10 yrs 10 yrs and and

more more

Daily and hourly with Daily and hourly with dischdisch

Pan Pan evaporationevaporation

3 years 3 years dailydaily dailydaily


DATA OBSERVATIONDATA OBSERVATION

As per IS / IMD StandardAs per IS / IMD StandardDischarge Observation by AV method/ calibrated Discharge Observation by AV method/ calibrated (model testing) Hydraulic structures(model testing) Hydraulic structuresReservoir levels in catchment with A-C curves, Reservoir levels in catchment with A-C curves, withdrawal and evaporationswithdrawal and evaporationsRF station min 1 per 600 sqkm (150 sq km in RF station min 1 per 600 sqkm (150 sq km in orographic area) 25% SRRG IMDorographic area) 25% SRRG IMDHydrometric min 1 per 2750sq km in coastal, Hydrometric min 1 per 2750sq km in coastal, 1000 sq km in mountains, 1875 sq km in 1000 sq km in mountains, 1875 sq km in between plains hills and undulating lands, 300 between plains hills and undulating lands, 300 sq km in small Islands WMOsq km in small Islands WMO


Data ProcessingData Processing

Quality of dataQuality of data

Filling up of short gapsFilling up of short gaps

Adjustment of recordsAdjustment of records

Consistency – Internal and externalConsistency – Internal and external

Data extension and generationData extension and generation

Analysis with AssumptionAnalysis with Assumption– sample representative of populationsample representative of population– homogeneous and randomhomogeneous and random– No presence of trends, jump and outliers No presence of trends, jump and outliers


Data Processing - StatisticsData Processing - Statistics

Mean : Annual, seasonal, monthly and Mean : Annual, seasonal, monthly and shorter durationshorter duration

Maxima, Minima, Median and selected Maxima, Minima, Median and selected percentile (75%, 90% etc)percentile (75%, 90% etc)

Range, Variance standard deviationRange, Variance standard deviation

Higher Moments skewness and KurtosisHigher Moments skewness and Kurtosis

Continuous record e.g. hydrograph and Continuous record e.g. hydrograph and SRRG chartsSRRG charts


DESIRED LENGTH OF WATER DESIRED LENGTH OF WATER AVAILABILTY SERIESAVAILABILTY SERIES

10 yrs for Diversion project10 yrs for Diversion project

25 years for within the year storage25 years for within the year storage

40 years for over the year storage40 years for over the year storage

Depending upon the predominant Depending upon the predominant component in complex systemcomponent in complex system


HYDROLOGY – SOME BASICSHYDROLOGY – SOME BASICS

Runoff estimation : Runoff estimation : As depth(mm/cm/inch)As depth(mm/cm/inch)As volume( Ha-m/ cum)As volume( Ha-m/ cum)As intensity ( discharge – cumecs/cusecs)As intensity ( discharge – cumecs/cusecs)

Rainfall Runoff relationship:Rainfall Runoff relationship:o Runoff = rainfall * RR coeffeciantRunoff = rainfall * RR coeffecianto Elaborate Water Balance Models – statistical Elaborate Water Balance Models – statistical

and determimisticand determimistic


HYDROLOGY – SOME BASICSHYDROLOGY – SOME BASICS

RunoffRunoff- Surface runoffSurface runoff- Sub surface runoffSub surface runoff- Ground water flowGround water flow

Mathematical equation of Hydrological cycle:Mathematical equation of Hydrological cycle:

P= E+ RP= E+ R


Factors affecting Evaporation (Loss Factors affecting Evaporation (Loss to Runoff)to Runoff)

Meteorological charactersitcsMeteorological charactersitcs

- Temperature : increase- Temperature : increase

- Wind : increase- Wind : increase

- Atmospheric pressure : decrease- Atmospheric pressure : decrease

- Soluble salts : decrease- Soluble salts : decrease

-. Heat storage in water bodies (deep -. Heat storage in water bodies (deep lakes) : decrease in summer but increase lakes) : decrease in summer but increase in winter (No change on annual values)in winter (No change on annual values)


Factors affecting Infiltration (Loss to Factors affecting Infiltration (Loss to runoff)runoff)

Geological characteristics CGeological characteristics Characteristics haracteristics of soilof soil

Characteristics of catchment surfaceCharacteristics of catchment surface

Fluid characteristicsFluid characteristics


HYDROLOGY – SOME BASICSHYDROLOGY – SOME BASICS Factors affecting runoffFactors affecting runoff

Factors affecting Run Off:Factors affecting Run Off:o precipitaion Characteristicsprecipitaion Characteristicso Shape and size of catchmentShape and size of catchmento TopographyTopographyo Storage characteristicsStorage characteristics


DESIGN FLOODDESIGN FLOOD

A flood hydrograph or instantaneous peak A flood hydrograph or instantaneous peak discharge adopted for a river control structure discharge adopted for a river control structure after accounting for hydrological and economic after accounting for hydrological and economic factors is called Design floodfactors is called Design flood corresponds to maximum tolerable riskcorresponds to maximum tolerable risk Project can sustain without substantial Project can sustain without substantial damage to its components as well as people and damage to its components as well as people and propertyproperty CAN BE EXCEEDEDCAN BE EXCEEDED Risk of damage is equivalent to probability of Risk of damage is equivalent to probability of occurrence of floods larger than Design Flood.occurrence of floods larger than Design Flood.


DESIGN FLOODDESIGN FLOOD

– Purpose: Safety of project components and affected Purpose: Safety of project components and affected people and property in the events of extreme Floodpeople and property in the events of extreme Flood

For safety of damFor safety of dam

For energy dissipation systemFor energy dissipation system

Extent of upstream submergenceExtent of upstream submergence

down stream damagesdown stream damages

– Proper selection: Additional cost of structures v/s Proper selection: Additional cost of structures v/s risk of losses to structures and affected people and risk of losses to structures and affected people and propertyproperty

– Absolute protection: UnrealisticAbsolute protection: Unrealistic– Increased risk: UnacceptableIncreased risk: Unacceptable


DESIGN FLOOD - CRITERIADESIGN FLOOD - CRITERIA

Storage - Storage - IS: 11223-IS: 11223-1985 1985

Classification. Gross storage (S)

Mm3 Head (H) m Design flood.

Small 0.5 to 10 7.5 to 12 100 Yr. flood Intermediate 10 to 60 12 to 30 SPF

Large >60 >30 PMF


DESIGN FLOOD - CRITERIADESIGN FLOOD - CRITERIA

Diversion Projects - Diversion Projects - IS 6966: Patt I IS 6966: Patt I – Free Board (Water way – capacity) 500 year Free Board (Water way – capacity) 500 year

or SPSor SPS– For other purposes - 50 yearsFor other purposes - 50 years

CD Works - IS 7784 Part I 1993 CD Works - IS 7784 Part I 1993

Diversion during construction - IS 10084 Diversion during construction - IS 10084 Part I 1982 Part I 1982


DESIGN FLOOD - METHODSDESIGN FLOOD - METHODS

Formulae Approach.Formulae Approach.– EmpiricalEmpirical– Envelop curvesEnvelop curves

Statistical approach, commonly known as Statistical approach, commonly known as Flood Frequency Approach.Flood Frequency Approach.

Hydrometeorological approach, commonly Hydrometeorological approach, commonly known as the Unit Hydrograph Approachknown as the Unit Hydrograph Approach



Envelop curves - PrincipleEnvelop curves - Principlemaximum floods per unit area experienced in one basin maximum floods per unit area experienced in one basin is quite likely to be experienced in nearby basin in the is quite likely to be experienced in nearby basin in the same region having same climatological and same region having same climatological and physiographic characteristics physiographic characteristics PMFs estimated by Central Water Commission (and PMFs estimated by Central Water Commission (and other organisations) between 1980-91 utilised for other organisations) between 1980-91 utilised for developing envelope curves for PMF peaks. developing envelope curves for PMF peaks. equation: equation: – Upper envelopesUpper envelopes Qu = 1585 A0.35Qu = 1585 A0.35– Average line,Average line, Qav = 398 A0.425Qav = 398 A0.425– Lower envelope,Lower envelope, QL = 100 A0.5QL = 100 A0.5



Statistical Methods:Statistical Methods:combination of numerous factors producing floods are combination of numerous factors producing floods are

matter of matter of purepure chance and chance and thereforetherefore are subject are subject to analysis according to the theory of probability. to analysis according to the theory of probability.

Applied on discharge data either directly observed at Applied on discharge data either directly observed at the site of study or estimated by the suitable the site of study or estimated by the suitable method method Annual peak flood series –excludes all second Annual peak flood series –excludes all second and third and so on rankings in the yearand third and so on rankings in the year Partial duration - all events above a certain Partial duration - all events above a certain threshold and INDEPENDENT are included in the threshold and INDEPENDENT are included in the analysisanalysis



Statistical Methods:Statistical Methods:

Fitting various probability distribution to the Fitting various probability distribution to the sample and estimation of the parameters of the sample and estimation of the parameters of the distribution;distribution;

Suitable for extreme valueSuitable for extreme value Have descriptive statistics similar to data setHave descriptive statistics similar to data set Does not contradict physical processDoes not contradict physical process

applying suitable test to identify the various applying suitable test to identify the various distributions which provides best fit; anddistributions which provides best fit; and

estimating the floods of different return periodestimating the floods of different return period



Hydrometeorolgical approachHydrometeorolgical approach


SEDIMENTATION STUDIESSEDIMENTATION STUDIES

Sediment in water:Sediment in water:– suspended sediment – Measurements donesuspended sediment – Measurements done– Bed load sediment -estimatedBed load sediment -estimated

Depends uponDepends upon– Type of catchment surfaceType of catchment surface– Flow in streamFlow in stream

Measurements of suspended sedimentMeasurements of suspended sedimentBed load estimated dependent on Bed load estimated dependent on – Suspended load concentration and textureSuspended load concentration and texture– Bed materialBed material– Taken as percent of suspended loadTaken as percent of suspended load



Effects –Effects –

Location of intakesLocation of intakes– Hydraulic functioningHydraulic functioning– Drawing silt load in intakes – proportional for irrigation Drawing silt load in intakes – proportional for irrigation

canal : excluded for power intakecanal : excluded for power intake

Reduction in storageReduction in storage– Ends economical usefulness Ends economical usefulness – Trapped sediments directly proportional to capacity Trapped sediments directly proportional to capacity

inflow ratio –Brune’s curve/ Churchill’s methodinflow ratio –Brune’s curve/ Churchill’s method



Till 1965 all sediment assumed to be deposited in dead Till 1965 all sediment assumed to be deposited in dead storage (= life of reservoir * average annual sediment load)storage (= life of reservoir * average annual sediment load)Later – empirical area reduction methodLater – empirical area reduction methodFull service time 50 years for irrigation and 25 years for Full service time 50 years for irrigation and 25 years for Hydro : Projected Area capacity for that time to be used in Hydro : Projected Area capacity for that time to be used in simulationssimulations– If problem serious (annual loss of capacity If problem serious (annual loss of capacity

>0.5% )simulations to use area capacity revised evry 10 >0.5% )simulations to use area capacity revised evry 10 years blockyears block

Hydraulic operations to remain possible Life of reservoir - Hydraulic operations to remain possible Life of reservoir - 100 years for irrigation and 70 years for Hydro : Projected 100 years for irrigation and 70 years for Hydro : Projected new zero elevation for that time to be used for location of new zero elevation for that time to be used for location of inlets to be above that levelinlets to be above that levelIS :12187 – 1987 read with IS :5477 part I-IV 1969IS :12187 – 1987 read with IS :5477 part I-IV 1969CBIP -19CBIP -19
