Water and Water Pollution. Chapter 11. Core Case Study: Water Conflicts. Water shortages in the Middle East Nile River Jordan Basin Tigris and Euphrates Rivers Peacefully solving the problems. Three Major River Basins in the Middle East. Fig. 11-1, p. 227. 11-1 Will We Have Enough Water?.
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Water and Water Pollution Chapter 11
Core Case Study: Water Conflicts • Water shortages in the Middle East • Nile River • Jordan Basin • Tigris and Euphrates Rivers • Peacefully solving the problems
Three Major River Basinsin the Middle East Fig. 11-1, p. 227
11-1 Will We Have Enough Water? • Concept 11-1A We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource. • Concept 11-1B One of every six people do not have sufficient access to clean water, and this situation will almost certainly get worse.
Importance and Availability of Water • Why is water so important? • Earth as a watery world – 71% • Freshwater availability – 0.024% • Poorly managed resource • Hydrologic cycle • Water pollution
Groundwater • Zone of saturation • Water table • Aquifers • Natural recharge • Lateral recharge
Unconfined Aquifer Recharge Area Evaporation and transpiration Precipitation Evaporation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Water table Infiltration Lake Infiltration Unconfined aquifer Less permeable material such as clay Confined aquifer Confining impermeable rock layer Fig. 11-2, p. 229
Surface Water • Surface runoff • Watershed (drainage) basin • Reliable runoff – 1/3 of total • Runoff use • Domestic – 10% • Agriculture – 70% • Industrial use – 20%
Case Study: Freshwater Resources in the United States • Uneven distribution • Contamination • Eastern U.S. • Western U.S. • Groundwater withdrawal – 50% • Water hot spots
Annual Precipitation and Water-deficit Regions of the Continental U.S. Fig. 11-3, p. 230
Average annual precipitation (centimeters) 81-122 More than 122 Less than 41 41-81 Acute shortage Shortage Adequate supply Metropolitan regions with population greater than 1 million Stepped Art Fig. 11-3, p. 230
Water Hot Spots in Western States Fig. 11-4, p. 231
Freshwater Shortages • Causes of water scarcity • Dry climate • Too many people • 1 of 6 people – no regular access to clean water
Stress on World’s River Basins Fig. 11-5, p. 231
Future Trends • United Nations Report • 2-7 billion people will face water shortages by 2050 • Effect of global warming? • Interconnections • Food • Economics • Social
11-2 How Can We Increase Water Supplies? • Concept 11-2A Groundwater used to supply cities and grow food is being pumped from aquifers in some areas faster than it is renewed by precipitation. • Concept 11-2B Using dams, reservoirs, and transport systems to transfer water to arid regions has increased water supplies in those areas, but has disrupted ecosystems and displaced people.
11-2 How Can We Increase Water Supplies? • Concept 11-2C We can convert salty ocean water to freshwater, but the cost is high, and the resulting salty brine must be disposed of without harming aquatic or terrestrial ecosystems.
Increasing Freshwater Supplies • Withdrawing groundwater • Dams and reservoirs • Transporting surface water • Desalination • Water conservation • Better use of natural hydrologic cycle
Trade-offs: Withdrawing Groundwater Fig. 11-6, p. 233
Degradation of a Nonrenewable Aquifer in Saudi Arabia Fig. 11-7, p. 233
Aquifer Depletion from Groundwater Overdraft in the United States Fig. 11-8, p. 234
Major irrigation well Well contaminated with saltwater Water table Sea level Saltwater Fresh groundwater aquifer Seafloor Interface Saltwater intrusion Interface Normal interface Fig. 11-9, p. 234
Groundwater Depletion Fig. 11-10, p. 234
Provides irrigation water above and below dam Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Provides water for drinking Deprives downstream cropland and estuaries of nutrient-rich silt Reservoir useful for recreation and fishing Risk of failure and devastating downstream flooding Can produce cheap electricity (hydropower) Reduces downstream flooding Disrpupts migration and spawning of some fish Fig. 11-11a, p. 235
Powerlines Reservoir Dam Powerhouse Intake Turbine Fig. 11-11b, p. 235
Ecological Services of Rivers Fig. 11-12, p. 236
California Water Project and Central Arizona Project Fig. 11-13, p. 237
Aral Sea Disaster (1) • Large-scale water transfers in dry central Asia • Salinity • Wetland destruction and wildlife • Fish extinctions and fishing
Aral Sea Disaster (2) • Wind-blown salt • Water pollution • Climatic changes • Restoration efforts
Shrinking Aral Sea Fig. 11-14, p. 237
Removing Salt from Seawater • Desalination • Distillation • Reverse osmosis • 15,000 plants in 125 countries
Major Problems with Desalination • High cost • Death of marine organisms • Large quantity of brine wastes • Future economics
11-3 How Can We Use Water More Sustainably? • Concept 11-3 We can use water more sustainably by cutting water waste, raising water prices, slowing population growth, and protecting aquifers, forests, and other ecosystems that store and release water.
Reducing Water Waste (1) • Benefits of water conservation • Worldwide – 65-70% loss • Evaporation, leaks • Water prices, government subsides, waste
Reducing Water Waste (2) • Improve irrigation efficiency • Improve collection efficiency • Use less in homes and businesses
Center pivot (efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler) Drip irrigation (efficiency 90–95%) Gravity flow (efficiency 60% and 80% with surge valves) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Above- or below-ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river. Fig. 11-15, p. 240
Reducing Irrigation Water Waste Fig. 11-16, p. 241
Reducing Water Waste Fig. 11-17, p. 241
Sustainable Water Use Fig. 11-18, p. 242
What Can You Do? Fig. 11-19, p. 242
11-4 How Can We Reduce the Threat of Flooding? • Concept 11-4 We can improve flood control by protecting more wetlands and natural vegetation in watersheds and by not building in areas subject to frequent flooding.
Benefits of Floodplains (1) • Highly productive wetlands • Provide natural flood and erosion control • Maintain high water quality • Recharge groundwater
Benefits of Floodplains (2) • Fertile soils • Nearby rivers for use and recreation • Flatlands for urbanization and farming
Dangers of Floodplains and Floods • Deadly and destructive • Human activities worsen floods • Failing dams and water diversion • Hurricane Katrina and the Gulf Coast • Removal of coastal wetlands