Introduction Hydrology and Water Resources

INTRODUCTIONHYDROLOGY AND WATER

RESOURCES

HYDROLOGY AND WATER RESOURCES

RG744INSTITUTE OF SPACE TECHNOLOGY

SEPTEMBER 25, 2013

HYDROLOGY: DEFINITION

NATURAL SCIENCE THAT DEALS WITH THE TRANSPORT AND DISTRIBUTION OF WATER (LIQUID, GAS, SOLID) IN THE ATMOSPHERE, ON AND BENEATH THE EARTH'S SURFACE

HYDROLOGY

• STUDY OF:

• Occurrence

• Circulation

• Storage

• Quality

• Distribution of surface and ground water on the earth

HYDROLOGY INCLUDES?

• DOMAIN OF HYDROLOGY INCLUDES:• Physical,

• Chemical and

• Biological processes/reactions of water in natural and man made environment

• STUDY OF HYDROLOGY MAY INCLUDE TOPICS FROM TRADITIONAL

• Fluid mechanics,

• Hydrodynamics,

• Water resources engineering

• Water quality and contaminant transport

SCOPE OF HYDROLOGY

• Maximum probable flood

• Water yield

• Groundwater development

• Maximum intensity and frequency of storms

HYDROLOGIC DATA REQUIRED?

1. CLIMATOLOGICAL DATA

2. HYDRO-METEOROLOGICAL DATA

3. PRECIPITATION RECORDS

4. STREAM-FLOW RECORDS

5. SEASONAL FLUCTUATION OF GW TABLE

6. EVAPORATION DATA

7. CROPPING PATTERN, CROPS AND THEIR CONSUMPTION

8. WATER QUALITY DATA (BOTH SURFACE AND GW)

9. ETC.

1.4 Billion Km3 of water on Earth

Distribution of Earth Water Resources

Reservoir Volume (cubic km

x 1,000,000) Percent of Total

Oceans 1370 97.25

Ice Caps/Glaciers 29 2.05

Deep Groundwater 5.3 0.38

Shallow Groundwater 4.2 0.30

Lakes 0.125 0.01

Soil Moisture 0.065 0.005

Atmosphere 0.013 0.001

Rivers 0.0017 0.0001

Biosphere 0.0006 0.00004

Water Inventory at Earth's Surface

http://www.livinglandscapes.bc.ca/thomp-ok/env-changes/water/introduction.html

DISTRIBUTION OF FRESH WATER ON EARTH

GLOBAL WATER USAGE TREND

• ACCELERATING

• 1975: 700 km3/y

• 2002: 6,000 km3/y

• CAUSES

• Population Increase

• Better Living Standards

• Others

HYDROLOGIC CYCLE

• Continuous process

• Water evaporated from water surfaces

• Moves inland as moist air masses

• Precipitation falls from clouds

HYDROLOGIC CYCLE

Water is conserved: Neither created nor destroyed

COMPONENTS OF HYDROLOGIC CYCLE

COMPONENTS OF HYDROLOGIC CYCLE

• PRECIPITATION • Major element that drives Hydrologic Cycle depending on various

weather parameters and systems

• INFILTRATION • Function of soil moisture conditions and soil type

• RUNOFF • Overland flow in a down gradient direction

• STORAGE• Surface and groundwater

• EVAPOTRANSPIRATION• Evaporation: the conversion of water to water vapor from a

water surface• Transpiration: loss of water vapor through plant tissues and

leaves

HYDROLOGIC ANALYSIS

• Hydrologic analysis is done to determine rainfall-runoff response from a watershed area

• Hydrologic Cycle is a complex series of processes but under well defined conditions with simple assumptions the response of a watershed can be made

PRECIPITATION

• When atmospheric moisture becomes so heavy to remain suspended in clouds

• All form of water that comes to earth from atmosphere (rainfall, snowfall, hail, frost and dew)

• Rainfall is the predominant form

• Ocean evaporation is the greatest source (90%)

PRECIPITATION IS VARIABLE !!!

• EXAMPLE: YEAR TO YEAR VARIATION

SOURCE: GLOBAL PRECIPITATION CLIMATOLOGY PROJECT (GPCP) BY GEWEX RADIATION PANEL (GRP)

PRECIPITATION

• SIMILAR MAP FOR THE REGION OF PAKISTAN (PAKISTAN METEOROLOGICAL DEPARTMENT)

HTTP://WWW.PAKMET.COM.PK/

• SOME FIGURES (AVERAGE ANNUAL RAINFALL)

• WEATHER AND CLIMATE OF PAKISTAN

SURFACE RUNOFF

• WATER THAT FLOWS OVER LAND AFTER STORM EVENTS

• QUANTITY DEPENDS ON:

• Climatic Factors: Rainfall frequency and intensity

• Geological Factors: surface permeability

• Geometrical Factors: shape of watershed, slope

• Biological Factors: Vegetation cover

• ZERO RUNOFF?

• RUNOFF = RAINFALL?

STORAGE: SURFACE WATER

• SURFACE WATER

• Reservoir: Artificial or naturally inland body of water used to store water to meet various demands

• Lake: Large naturally occurring inland body of water

• Wetlands: Natural or artificial areas of shallow water or saturated soils that support certain water plants

STORAGE: GROUNDWATER

• GROUNDWATER• Water infiltrating through soil cover of a land surface to

a huge waterbody underground

• In a state of continuous movement

• Difficult to extract all by practicable means

• Groundwater recharge: dynamic resource that is replenished by precipitation, seepage from surface waterbodies, conveyance system return flow from irrigation water.

• Governed by rainfall intensity and soil and aquifer conditions

EVAPOTRANSPIRATION

• COMBINATION OF EVAPORATION AND TRANSPIRATION

WATERSHED

• THE GEOGRAPHICAL AREA THAT CONTRIBUTES TO THE FLOW

OF A RIVER

• Basic hydrologic unit within which all measurements, calculations, and predictions are made in hydrology

• To calculate runoff (volume) expected from a given rainfall event that falls over an area

• Varies in size from few acres to thousands of square miles

WATERSHED

• Watershed delineation based on topographic or elevation data

• Watershed divide (ridge line) separates two watersheds that drain into different outlets

• Area encompassed by divide is the watershed area

• Runoff originating at higher elevations moves towards lower elevation in a direction perpendicular to the contour lines to the nearest stream

• Larger the watershed area greater the surface runoff rate and stream flow rate

HYETOGRAPH?

• DISTRIBUTION OF RAINFALL OVER TIME

ISOHYETAL MAPS

ISOHYETAL MAPS

HYDROGRAPH

• Hydrologic response of rainfall at the outlet of an area

• A plot of discharge in the channel vs. time (cubic feet per second)

HYDROGRAPH RESPONSE SHAPE DEPENDS ON?

EFFECT OF BASIN CHARACTERISTICS ON THE FLOOD HYDROGRAPH

IMPACT OF URBANIZATION

WATER RESOURCES POTENTIAL (WRP)

• UTILIZABLE SURFACE WATER POTENTIAL: AMOUNT OF WATER THAT CAN BE FULLY USED WITHOUT WASTAGE TO SEA

INTERNATIONAL INDICATORS TO MEASURE WRP

• HOME ASSIGNMENT: SEARCH THIS TOPIC ON INTERNET TO DISCUSS IN THE NEXT CLASS

FUTURE DEVELOPMENT OF WATER RESOURCES

• Sustainable water utilization

• Conservation of water (cleaner practices)

• Non-consumptive use

INDUS RIVER BASIN

• STATISTICAL FACTS AND FIGURES• Drainage/catchment area in Territory of

Pakistan = 692,700 Km2

• Draining into the Arabian Sea

• Mean annual flow of Indus basin rivers=187km3.

• Mean average rainfall (Pak) = 205 mm

• Evapotranspiration = 1700-2100 mm

• Major Irrigation Projects: IBIS

WATER TREATY 1960

• BETWEEN INDIA AND PAKISTAN

• WATER RIGHTS OF INDIA AND PAKISTAN

• WESTERN RIVERS (INDUS, JHELUM AND CHENAB): PAKISTAN

• EASTERN RIVERS (RAVI, SUTLEJ AND BEAS): INDIA

HYDROLOGY VS. HYDRAULICS MODELS?

• HYDROLOGY (SURFACE)

• how water moves into the drainage system

• HYDRAULICS

• water going through the drainage

UNITS

• cfs or cusec• ac-ft (1 ac = 43560 ft2)

• MGD (1 MGD = 1.55 cfs)• 1 m3/s or cumec (1 m3/s = 22.8 MGD)• 1 gal (1 ft3 = 7.48 gal)• 1 mile2 (1 mile2 = 640 acres)• 1 mile = 5280 ft