PRACTICING PRACTICING HYDROLOGY AN HYDROLOGY AN
OVERVIEWOVERVIEW
A.K. LohaniA.K. LohaniScientist FScientist F
National Institute of HydrologyNational Institute of HydrologyRoorkeeRoorkee
[email protected]@gmail.com
HYDROLOGYHYDROLOGY
• The break-up of the word hydrology is : "hydro" and The break-up of the word hydrology is : "hydro" and "logy". "Hydro" means water and "logy" means science."logy". "Hydro" means water and "logy" means science.
DefinitionDefinition
• Hydrology is the science that treats the waters of the Hydrology is the science that treats the waters of the Earth, their occurrence, circulation and distribution, their Earth, their occurrence, circulation and distribution, their chemical and biological properties and their reaction with chemical and biological properties and their reaction with their environment, including their relation to living things. their environment, including their relation to living things. The domain of hydrology embraces the full life history of The domain of hydrology embraces the full life history of water on the Earth.water on the Earth.
Hydrological Cycle Hydrological Cycle
The cycle may be divided into three The cycle may be divided into three principal phases. principal phases.
(a) precipitation (a) precipitation (b) evaporation and(b) evaporation and
(c) runoff-surface and ground water. (c) runoff-surface and ground water.
HYDROLOGIC CYCLEHYDROLOGIC CYCLE
Hydrology is the science that treats the water of the Earth, their Hydrology is the science that treats the water of the Earth, their occurrence, circulation, movement and distribution, their chemical and occurrence, circulation, movement and distribution, their chemical and
biological properties and their reaction with their environment, biological properties and their reaction with their environment, including their relation to living things.The domain of hydrology including their relation to living things.The domain of hydrology
embraces the full life history of water on the earth.embraces the full life history of water on the earth.
NATIONAL INSTITUTE OF NATIONAL INSTITUTE OF HYDROLOGYHYDROLOGY
ROORKEEROORKEE
HYDROLOGICAL CYCLEHYDROLOGICAL CYCLE
* PRECIPITATION PHASE- RAIN- SNOW
* RUNOFF PHASE- OVERLAND FLOW- CHANNEL FLOW- INTER FLOW- BASE FLOW
* EVAPORATION PHASE
- FROM INTERCEPTION STORAGE- FROM WATER BODIES- FROM UNSATURATED ZONE- FROM SATURATED ZONE- TRANSPIRATION THROUGH PLANTS
HYDROLOGIC CYCLE HYDROLOGIC CYCLE [Contd….][Contd….]
HYDROLOGIC PROCESSES AND THEIR INTERACTION
>INTERCEPTION
>INFILTRATION
>OVERLAND FLOW
>FLOW FROM DEPRESSION STORAGES
>CHANNEL FLOW
>FLOW THROUGH UZ AND SOIL MOISTURE
>FLOW THROUGH SZ AND WATER TABLE
>INTERACTION OF OVERLAND FLOW AND UZ
>INTERACTION OF CHANNEL FLOW AND SZ
>INTERACTION OF UZ AND SZ
Global scaleGlobal scale
Catchment Scale
Human Influence on Hydrologic CycleHuman Influence on Hydrologic Cycle
(a) Effects of agricultural changes(a) Effects of agricultural changes
(b) Effects of urbanisation(b) Effects of urbanisation
(c) Effects of forest activities(c) Effects of forest activities
(d) Effects of highway development (d) Effects of highway development
(e) Effects of mining(e) Effects of mining
(f) Effects of structural changes (f) Effects of structural changes
Human Influence on Hydrologic Cycle…Human Influence on Hydrologic Cycle…
• Space-Time Scales in HydrologySpace-Time Scales in Hydrology
• Water Resources AssessmentWater Resources Assessment
• Various phases must be considered with the catchment. Various phases must be considered with the catchment.
These have been classified as the phases of :These have been classified as the phases of :(i) Land surfaces;(i) Land surfaces;(ii) River channel networks;(ii) River channel networks;(iii) Reservoirs; and(iii) Reservoirs; and(iv) Sub-surface(iv) Sub-surface
SPACE-TIME SCALES IN HYDROLOGY
TIME SCALES
* HOURLY* DAILY* WEEKLY* TEN DAILY* MONTHLY* SEASONAL* ANNUAL
HYDROLOGIC BUDGET
INFLOW SYSTEM OUTFLOW
DRAINAGE BASIN AS A BLACK BOX SYSTEM
I(t)
Q(t)
S(t)
SS(t)
DRAINAGE BASIN AS A RESERVOIR
)()()(
tQtIt
tS
HYDROLOGIC BUDGETHYDROLOGIC BUDGET
WATER BALANCEWATER BALANCE
Hydrological Water Balance Hydrological Water Balance
The equation is based on the concept of continuity as follows: The equation is based on the concept of continuity as follows: Input to the system - Outflow from the system Input to the system - Outflow from the system = Change in storage in the system= Change in storage in the systemThe various components of the above continuity equation can be The various components of the above continuity equation can be
represented in equation form as: represented in equation form as: P + Input = Q + ET + Export + Sm + Sg + Sd + L P + Input = Q + ET + Export + Sm + Sg + Sd + L P + (Ic + Ig) = Q +ET +(Oc + Og) + Sm + Sg + Sd + L P + (Ic + Ig) = Q +ET +(Oc + Og) + Sm + Sg + Sd + L where, P = precipitationwhere, P = precipitation Ic = surface supplies through rivers, canals and drainage from outside the Ic = surface supplies through rivers, canals and drainage from outside the
basinbasinIg = inflow to the groundwater from other basinsIg = inflow to the groundwater from other basinsQ = runoffQ = runoffET = evaporation and evapotranspiration ET = evaporation and evapotranspiration Oc = surface supplies going out to other basins Oc = surface supplies going out to other basins Og = ground water outflow from the basin to other basinsOg = ground water outflow from the basin to other basinsSm = change in soil moistureSm = change in soil moistureSg = change in ground water storage Sg = change in ground water storage Sd = change in depression storage Sd = change in depression storage L = loss through deep percolation L = loss through deep percolation
Ground Water Balance Ground Water Balance
Considering the various sources of recharge and charge to Considering the various sources of recharge and charge to the ground water reservoir and change in storage in the the ground water reservoir and change in storage in the ground water, the basic equation of ground water balance ground water, the basic equation of ground water balance based on the concept of continuity can be written as: based on the concept of continuity can be written as: Rr + Rc + RI + Ig + Is = Tp + Og + ET + Es + Sg + L Rr + Rc + RI + Ig + Is = Tp + Og + ET + Es + Sg + L where, Rr = natural recharge from precipitationwhere, Rr = natural recharge from precipitationRc =Rc = recharge due to seepage from rivers, canals, recharge due to seepage from rivers, canals,
water courses, ponds, reservoirs, etc. water courses, ponds, reservoirs, etc. RI = recharge from irrigation and other activities RI = recharge from irrigation and other activities Is = influent seepage Is = influent seepage Tp = withdrawal from groundwater storage Tp = withdrawal from groundwater storage ET = evaporation and evapotranspiration from ground ET = evaporation and evapotranspiration from ground
water water Es = effluent seepage Es = effluent seepage
Water Use Balance Water Use Balance
Water use for the growth of crops and other vegetation comes Water use for the growth of crops and other vegetation comes from their root zone. Considering the various sources of from their root zone. Considering the various sources of supply to and losses from the root zone of crops and vegetation supply to and losses from the root zone of crops and vegetation and the change in the soil moisture of the root zone, the water and the change in the soil moisture of the root zone, the water use balance equation can be written for irrigated areas, use balance equation can be written for irrigated areas, unirrigated areas and for water bodies as follows:unirrigated areas and for water bodies as follows:
For irrigated crops:For irrigated crops:
E' = Cc + T'p + IT + PE + Mg - Lc - LI E' = Cc + T'p + IT + PE + Mg - Lc - LI where, E' = evaporation from irrigated crops where, E' = evaporation from irrigated crops Cc = canal suppliesCc = canal suppliesT'p = supply from groundwater storage for irrigation T'p = supply from groundwater storage for irrigation IT = irrigation supplies from drains and tanks IT = irrigation supplies from drains and tanks Mg = contribution from groundwater irrigated fieldsMg = contribution from groundwater irrigated fieldsLc = losses from canals and water courses Lc = losses from canals and water courses LI = losses from irrigation fieldsLI = losses from irrigation fields
For unirrigated cropsFor unirrigated crops
E" = P'E + M'g + E'T E" = P'E + M'g + E'T where E" = evapotranspiration from vegetation, unirrigated crops where E" = evapotranspiration from vegetation, unirrigated crops
and natural landand natural landP'E = effective precipitation for vegetation and unirrigated fields P'E = effective precipitation for vegetation and unirrigated fields Mg = contribution from ground water for forests, trees and Mg = contribution from ground water for forests, trees and
unirrigated fieldsunirrigated fields
For water bodies For water bodies
E = Er + Ec + Ew E = Er + Ec + Ew where, E = evaporation from water surface where, E = evaporation from water surface Er = evaporation from surfaces in rivers, drains, etc. Er = evaporation from surfaces in rivers, drains, etc. Ec = evaporation from canals, water courses, etc. Ec = evaporation from canals, water courses, etc. Ew = evaporation from other water bodies Ew = evaporation from other water bodies It may be noted that It may be noted that ET = E' + E" + E ET = E' + E" + E
HYDROLOGIC MODELLING* IDENTIFICATION OF THE HYDROLOGICAL PROBLEMS* DATA AVAILABLIITY* DATA COLLECTION* DATA PROCESSING
- PRELIMINARY PROCESSING- SECONDARY PROCESSING
* INVENTORY FOR THE STUDY AREA* IDENTIFICATION OF MODEL STRUCTURE* USE OF AN EXISTING MODEL (OR DEVELOP A NEW MODEL)* MODEL CALIBRATION* MODEL VALIDATION* MODEL APPLICATION
DATA REQUIREMENT
PHYSICAL DATA* SOIL AND LAND USE MAPS* FLOOD MAPS* SNOW MAPS* EROSION MAPS* PHYSICAL PROPERTIES OF SOILS & SOIL
DEPTHS* PHYSICAL PROPERTIES OF CROPS & PLANTS* GEOMORPHOLOGICAL CHARACTERISTICS* RIVER CROSS SECTIONS AND L-SECTIONS* AQUIFER CHARACTERISTICS
DATA REQUIREMENT (CONTD…)* HYDROMETEOROLOGICAL TIME SERIES
- RAINFALL DATA- PAN-EVAPORATION DATA- OTHER CLIMATOLOGICAL DATA
* HYDROLOGICAL TIME SERIES DATA- WATER LEVEL AND STREAM FLOW DATA- GROUND WATER LEVEL DATA- PUMPING DATA- SOIL MOISTURE DATA
* UTILISATION DATA- RESERVOIR OPERATION DATA
HYDROLOGICAL MODEL CALIBRATION
* TRIAL AND ERROR METHOD
* AUTOMATIC OPTIMISATION TECHNIQUE
* COMBINATION OF ‘TRIAL & ERROR’ & ‘AUTOMATIC OPTIMISATION TECHNIQUE’
HYDROLOGICAL MODEL VALIDATION
* VISUAL OBSERVATION OF OBSERVED OUTPUT AND MODEL OUTPUT PLOTS
* EVALUATION OF PERFORMANCE CRITERIA
UNCERTAINTIES IN HYDROLOGICAL MODELLING
* UNCERTAINTIES IN INPUT
* UNCERTAINTIES IN MODEL STRUCTURE
* UNCERTAINTIES IN MODEL PARAMETERS
* UNCERTAINTIES IN OUTPUT
HYDROLOGICAL MODELS* DETERMINISTIC MODELS
- BLACK BOX MODEL- CONCEPTUAL MODEL
# LUMPED# DISTRIBUTED
- PHYSICALLY BASED DISTRIBUTED MODELS
* STOCHASTIC AND STATISTICAL MODELS
* OPTIMISATION MODEL (LP, DP, Etc.)
REGIONAL HYDROLOGY* IDENTIFICATION OF REGION
* TESTING OF REGIONAL HOMOGENEITY
* EVALUATION OF HYDROLOGICAL VARIABLES FOR
THE GAUGED CATCHMENTS OF THE REGION
* EVALUATION OF PHYSIOGRAPHIC AND
GEOMORPHOLOGIC CHARACTERISTICS OF GAUGED
CATCHMENTS
* DEVELOPMENT OF REGIONAL RELATIONSHIP
* EVALUATION OF PHYSICAL CHARACTERISTICS FOR
UNGAUGED CATCHMENT
* EVALUATION OF HYDROLOGICAL VARIABLES USING
REGIONAL RELATIONSHIP FOR UNGAUGED
CATCHMENTS
HYDROLOGICAL PROBLEMSHYDROLOGICAL PROBLEMS
Some of the important problems of applied hydrology, hydrologists Some of the important problems of applied hydrology, hydrologists come across are:come across are:
(i)(i) Data managementData management- Hydrologic instrumentation & measurements- Hydrologic instrumentation & measurements- Data collection network- Data collection network- Data storage and retrieval- Data storage and retrieval- Data processing- Data processing- Data generation- Data generation
(ii)(ii) Hydrologic DesignHydrologic Design(iii)(iii) Hydrologic System OperationHydrologic System Operation(iv)(iv) Flood and its managementFlood and its management(v)(v) Drought and its managementDrought and its management(vi)(vi) Waterlogging and drainageWaterlogging and drainage(vii)(vii) Urban drainageUrban drainage(viii)(viii) Water quality and environmentWater quality and environment
(ix)(ix) Conjunctive uses of surface and ground waterConjunctive uses of surface and ground water(x)(x) SalinitySalinity(xi)(xi) Salt water intrusionSalt water intrusion(xii)(xii) Coastal drainageCoastal drainage(xiii) Over exploitation of ground water (Ground water (xiii) Over exploitation of ground water (Ground water
management)management)(xiv) Soil Erosion(xiv) Soil Erosion(xv) Reservoir Sedimentation(xv) Reservoir Sedimentation(xvi) Global Warming and Climate Change(xvi) Global Warming and Climate Change(xvii) Glacier, snow and ice melt(xvii) Glacier, snow and ice melt(xviii) Crop water requirements & Irrigation Scheduling(xviii) Crop water requirements & Irrigation Scheduling(xix) Impacts of watershed developments & land use (xix) Impacts of watershed developments & land use
changeschanges(xx)(xx) Hydrological problems of Lakes and TanksHydrological problems of Lakes and Tanks(xxi) Water Resources Assessment(xxi) Water Resources Assessment
APPLICATIONS OF APPLICATIONS OF HYDROLOGYHYDROLOGY
• Flood ControlFlood Control
• Drought MitigationDrought Mitigation
• Water SupplyWater Supply
• Pollution ControlPollution Control
• Urban DevelopmentUrban Development
• Industrial DevelopmentIndustrial Development
• Design of Hydraulic worksDesign of Hydraulic works
• Agricultural ProductionAgricultural Production
• Energy Resources DevelopmentEnergy Resources Development• LLand Conservationand Conservation• Environmental-Impact Environmental-Impact
AssessmentAssessment• Land use ChangeLand use Change• Forest and Wildlife ManagementForest and Wildlife Management• Military OperationsMilitary Operations• Rural DevelopmentRural Development• NavigationNavigation• RecreationRecreation• FisheriesFisheries
CONCLUDING REMARKS
* COMPUTERISATION OF THE TIME SERIES DATA
* REGULAR PROCESSING OF THE TIME SERIES DATA
* DATA STORAGE & RETRIEVAL FOR THE PROCESSED DATA
* APPLICATION OF GIS AND REMOTE SENSING FOR
PROVIDING HYDROLOGICAL MAPS IN DIGITAL FORM
* INTERFACING OF SPATIAL DATA BASE WITH TIME
SERIES DATA BASE
* INTERFACING OF SPATIAL AND TEMPORAL DATA BASES
WITH HYDROLOGICAL MODELS
Thank You !!Thank You !!
