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WATER RESOURCES

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  1. WATER RESOURCES PHYSICAL PROPERTIES, AVAILABILITY, SHORTAGES, SUSTAINABLITY

  2. Key Concepts • The physical properties of water • Availability of fresh water • Methods of increasing freshwater supplies • Using water more efficiently • Problems associated with flooding

  3. Water’s Importance • 71% Earth’s surface…water • 60% tree’s weight…water • 50-65% animal tissue…water • Water for survival and leisure • Carves surface features, dilutes pollution, moderates climates

  4. Properties • Hydrogen bonds: major factor determines properties • Liquid over wide temperature ranges due to strong forces of attraction between water molecules • Store large amounts of heat without large temperature change; evaporative and cooling properties; absorbs heat as it vaporizes; releases heat as it condenses • Universal solvent: dissolves many compounds; pH regulator • UV filter • Cohesive forces • Expands on freezing unlike most liquids

  5. Water’s Unique Properties Great dissolving power Carries dissolved nutrients into tissue Flush waste products out of tissue All-purpose cleanser Remove and dilute water-soluble wastes pH Helps maintain balance between acids and bases Adhesion and cohesion Surface tension Wetting ability Expands when it freezes Ice floats

  6. - - - - - - O O O H H H H H H + + + + + + Hydrogen bonds Covalent bonds

  7. 14 -2 Supply, renewal and use of water • 97.4% too salty for use as fresh water • Remaining 2.6% in ice, glaciers, deep groundwater…we have access to 0.014% as soil moisture, ground water, water vapor, lakes, streams IF: World’s water supply = 100L(26gallons), our USABLE amount would be .014L(2.5 teaspoons)

  8. Freshwater Readily accessible freshwater Groundwater 0.592% Biota 0.0001% Lakes 0.007% Rivers 0.0001% 0.014% Ice caps and glaciers 1.984% Soil moisture 0.005% Atmospheric water vapor 0.001% Supply of Water Resources Fig. 14-2 p. 314

  9. Global population Canada has only .5 % of world pop. But 20% of freshwater Annual precip. Divides countries into have/have nots

  10. Water Words Surface runoff: precip that does not infiltrate ground or return to atmosphere Reliable Runoff: 2/3 runoff is lost annually by floods Watershed (drainage basin): region from which water drains into a lake, stream Groundwater : water that infiltrates into voids in soil Zone of saturation: found below surface soils Water table: located at top of zone of saturation Aquifers: porous saturated layers of sand, gravel or bedrock Recharge area: area of land through which water passes into an aquifer Natural Recharge: natural replenishment of aquifers

  11. Groundwater

  12. Fresh water • World use: since 1900 world use of reliable runoff increased. Irrigation largest cause.. Humans withdraw 35% of runoff, 20% left in streams. Projections show that human use will exceed available reliable runoff in many areas • U.S. fresh water: plenty of water in wrong place at wrong time

  13. Use of Water Resources United States Agriculture 41% Power cooling 38% Industry 11% Public 10% • Humans use about 50% of reliable runoff • Agriculture • Industry • Domestic • Power Plants

  14. 5,500 5,000 4,500 4,000 3,500 3,000 Water use (cubic kilometers per year) 2,500 2,000 1,500 1,000 500 1900 1920 1940 1960 1980 2000 Total use Agricultural use Industrial use Domestic use Year

  15. 14-3 Water Shortages • Causes: • Dry climate, drought, desiccation(soil drying due to deforestation, overgrazing), water stress (low per capita availability), water scarcity. • Solutions: • Increase supply by: dams and reservoirs, transport surface water, withdraw groundwater, desalination, waste less, import more food

  16. Too Little Water Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million • Dry climate • Air circulation patterns • Drought • 21 days+ • Precipitation <70% • Increased evaporation • Desiccation • Drying of the soil • Water stress • Low per capita availability • Caused by increased population • Limited runoff levels

  17. Water stressed – reliable runoff per person below 1700 cu meters per year Water scarcity – per capita availability below 1000 cu meter per year • 500 million people live in countries that are either water stressed or water scarce • limited access (live far away) • arrives during short periods • hydrological poverty • Collect water from unsafe sources • Purchase from private vendor

  18. Increasing Fresh Water Supplies Build dams and reservoirs to store runoff Bring surface water from another area Withdraw groundwater. Convert salt water to fresh water Waste less water Import food to reduce water use

  19. 14-4 Dams and Reservoirs Purpose: capture and store runoff, release when needed • Pros: • Control floods, produce power, supply irrigation, recreation • Cons: • Major rivers can run dry, causes drought downstream, salt water infiltration further upstream • Dam removal

  20. Provides water for year-round irrigation of cropland Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Provides water for drinking Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Risk of failure and devastating downstream flooding Can produce cheap electricity (hydropower) Downstream flooding is reduced Migration and spawning of some fish are disrupted Fig. 14-13a, p. 317

  21. Downstream cropland and estuaries are deprived of nutrient-rich silt Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Downstream flooding is reduced Reservoir is useful for recreation and fishing Provides water for year-round irrigation of cropland Can produce cheap electricity (hydropower) Migration and spawning of some fish are disrupted Using Dams and Reservoirs to Supply More Water

  22. Ecological Services of Rivers • Deliver nutrients to the sea which helps to sustain coastal fisheries • Deposit silt that maintains deltas • Purify water • Renew and nourish wetlands • Provide habitats for aquatic life • Conserve species diversity

  23. Beijing RUSSIA YELLOW SEA MONGOLIA CHINA Shanghai Wunan Jailing River Yichang Chongquing Yangtze River CHINA Three Gorges Dam Reservoir EAST CHINA SEA NEPAL BHUTAN BANGLADESH PACIFIC OCEAN VIETNAM INDIA BURMA LAOS China’s Three Gorges Dam

  24. China’s Three Gorges Dam Project: What are the pros and cons? Pros: hydro power, hold flood waters; Cons: flood farmlands, pollution due to decrease in water flow

  25. Case Study: The Colorado Basin – an Overtapped Resource Lake Powell, is the second largest reservoir in the U.S. It hosts one of the hydroelectric plants located on the Colorado River.

  26. IDAHO WYOMING Dam The Colorado River Basin Aqueduct or canal Salt Lake City Grand Junction Upper Basin Denver Lower Basin UPPER BASIN UTAH COLORADO Lake Powell Grand Canyon Glen Canyon Dam Las Vegas NEW MEXICO Boulder City ARIZONA CALIFORNIA Albuquerque LOWER BASIN Los Angeles Palm Springs Phoenix 0 100 mi. San Diego Yuma 0 150 km Mexicali Tucson All-American Canal Gulf of California MEXICO

  27. CALIFORNIA NEVADA UTAH Shasta Lake Sacramento River Sacramento North Bay Aqueduct San Francisco Fresno South Bay Aqueduct Colorado River Los Angeles Aqueduct ARIZONA California Aqueduct Central Arizona Project Los Angeles Phoenix San Diego Colorado River Aqueduct Tucson MEXICO 14-5 Water Transfers: Case Studies • California Water Project : large scale water transfers from one watershed to another by aqueducts • James Bay Watershed Transfer: will reverse flow of 19 major rivers and cause massive flooding. Project halted 1994 • Aral Sea Water Transfer(Soviet Union): increase sea salinity, surface area decrease, river system supply reduced

  28. 14-6 Other sources of freshwater • Advantages of groundwater removal: removed as needed year round, not lost by evaporation, less expensive to develop. (aquifers provide water to 1/3 of world populations) Disadvantages of withdrawing groundwater: water table lowering; aquifer depletion/ subsistence. Intrusion of salt water, reduced stream flows, Ogallala Aquifer Ways to Prevent or slow GW depletions: -Control pop. Growth, not plant water intensive crops, waste less irrigation.

  29. Problems with Using Groundwater Original water table Initial water table Cone of depression Lowered water table • Water Table Lowering

  30. Ways to increase supplies of fresh water • 1. Desalinization: removal of salt from ocean water. • How Useful??? 13,300 plants today supply just 0.2% of water today • Methods: distillation, reverse osmosis • Disadvantages: expensive, produces large quantities of wastewater brine. • Beneficial in coastal cities in arid countries. Better reverser osmosis; what to do with all the salt?

  31. Using Water More Efficiently • Reduce losses due to leakage • 70% of all water use is lost through evaporation,leakage from pipes • Reform water laws • subsidy policies, riparian rights • Improve irrigation efficiency • Improving manufacturing processes • Water efficient landscaping • Water efficient appliances