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Introduction Hydrology and Water Resources

Introduction Hydrology and Water Resources. Hydrology and Water Resources RG744 Institute of Space Technology September 09, 2015. Hydrology: Definition.

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Introduction Hydrology and Water Resources

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  1. IntroductionHydrology and Water Resources Hydrology and Water Resources RG744 Institute of Space Technology September 09, 2015

  2. 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

  3. Hydrology • Study of: • Occurrence • Circulation • Storage • Quality • Distribution of surface and ground water on the earth

  4. 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

  5. Scope of hydrology • Maximum probable flood • Water yield • Groundwater development • Maximum intensity and frequency of storms

  6. Hydrologic data required? • Climatological data • Hydro-meteorological data • Precipitation records • Stream-flow records • Seasonal fluctuation of GW table • Evaporation data • Cropping pattern, crops and their consumption • Water quality data (both surface and gw) • Etc.

  7. Why we need to manage WORLD’S WATER RESOURCES?

  8. Distribution of Earth Water Resources 1.4 billion Km3 of water on Earth

  9. Water Inventory at Earth's Surface http://www.livinglandscapes.bc.ca/thomp-ok/env-changes/water/introduction.html

  10. Distribution of Fresh Water on Earth

  11. Global Water Usage Trend • Accelerating • 1975: 700 km3/y • 2002: 6,000 km3/y • Causes • PopulationIncrease • Better Living Standards • Others

  12. Hydrologic Cycle • Continuous process • Water evaporates from water surfaces • Moves inland as moist air masses • Precipitation falls from clouds

  13. Hydrologic Cycle Water is conserved: Neither created nor destroyed

  14. Components of Hydrologic Cycle Quantity of each component depends on?

  15. 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

  16. 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

  17. 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%)

  18. Precipitation is Variable !!! • Example: Year to year variation

  19. Source: Global Precipitation Climatology Project (GPCP) by GEWEX Radiation Panel (GRP)

  20. Precipitation • similar map for the region of Pakistan (Pakistan meteorological department) http://www.pmd.gov.pk/ • Some figures (average annual rainfall) • Weather and climate of Pakistan

  21. 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?

  22. 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

  23. 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

  24. Evapotranspiration • Combination of Evaporation and Transpiration

  25. 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

  26. 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

  27. Hyetograph? • Distribution of rainfall over time

  28. Isohyetal maps

  29. Isohyetal maps

  30. Hydrograph • Hydrologic response of rainfall at the outlet of an area • A plot of discharge in the channel vs. time (cubic feet per second)

  31. Hydrograph response shape depends on?

  32. Effect of Basin Characteristics on the flood hydrograph

  33. Impact of Urbanization

  34. Water Resources Potential (WRP) • Utilizable surface water potential: amount of water that can be fully used without wastage to sea

  35. International Indicators to measure WRP • Home Assignment: Search this topic on internet to discuss in the next class

  36. Future Development of Water Resources • Sustainable water utilization • Conservation of water (cleaner practices) • Non-consumptive use

  37. 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

  38. 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

  39. Hydrology vs. Hydraulics models? • Hydrology (surface) • how water moves into the drainage system • Hydraulics • water going through the drainage

  40. 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

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