1. Chapter 14 Water

2. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  covers 71% of the Earth’s surface  regulates Earth’s climate  dilutes wastes  sculpts earth’s surface,  major habitat

3. Supply  97% in oceans  3% fresh water  2.997% in ice caps glaciers .003% available to us

4. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  mostly to irrigate crops(69%)  energy production- 23%  industrial usage highest in Europe and N.America (US) Figure 14-2

5. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  Some precipitation infiltrates the ground and is stored in soil and rock (groundwater).  Water that does not sink into the ground or evaporate into the air runs off (surface runoff) into bodies of water. The land from which the surface water drains into a body of water is called its watershed or drainage basin. The land from which the surface water drains into a body of water is called its watershed or drainage basin.

6. Watersheds - drainage basins  areas of land that drain into bodies of surface water  water flowing off land into these bodies is called surface runoff

7. Fig. 14-3, p. 308 Unconfined Aquifer Recharge Area Precipitation Evaporation and transpirationEvaporation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Infiltration Water table Lake Infiltration Unconfined aquifer Confined aquifer Confining impermeable rock layer Less permeable material such as clay

8. Surface water  precipitation that does not soak into the ground or return to the atmosphere by evaporation  streams, lakes, wetlands, reservoirs

9. Groundwater  precipitation infiltrates the ground and fills pores in soil and rocks  zone of saturation - all available soil and rock spaces filled by groundwater

10. Water Table  upper surface of zone of saturation poorly demarcated between saturated soil and rock and unsaturated soil and rock  falls in dry weather and rises in wet weather

11. Cone of depression §withdrawal rate of aquifer exceed natural recharge rate, §water table around withdrawal well lowered §creates a waterless volume §any pollution discharged onto land above will be pulled directly into well

12. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  We currently use more than half of the world’s reliable runoff of surface water and could be using 70-90% by 2025.  About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources.  Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%).

13. Water in the United States  Average precipitation (top) in relation to water-deficit regions and their proximity to metropolitan areas (bottom). Figure 14-4

14. Case Study: Freshwater Resources in the United States  17 western states by 2025 could face intense conflict over scarce water needed for urban growth, irrigation, recreation and wildlife. Figure 14-5

15. Stress on the World’s River Basins  Comparison of the amount of water available with the amount used by humans. Figure 14-6

16. TOO LITTLE FRESHWATER  Cities are outbidding farmers for water supplies from rivers and aquifers.  Countries are importing grain as a way to reduce their water use.  More crops are being used to produce biofuels.  Our water options are: Get more water from aquifers and rivers, desalinate ocean water, waste less water. Get more water from aquifers and rivers, desalinate ocean water, waste less water.

17. WITHDRAWING GROUNDWATER TO INCREASE SUPPLIES  Most aquifers are renewable resources unless water is removed faster than it is replenished or if they are contaminated.  Groundwater depletion is a growing problem mostly from irrigation. At least one-fourth of the farms in India are being irrigated from overpumped aquifers. At least one-fourth of the farms in India are being irrigated from overpumped aquifers.

18. Other Effects of Groundwater Overpumping  Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater. Figure 14-11

19. Other Effects of Groundwater Overpumping  Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater. Figure 14-10

20. Groundwater Pumping in Saudi Arabia (1986 – 2004)  Irrigation systems from the nonrenewable aquifer appear as green dots. Brown dots are wells that have gone dry. Figure 14-9

21. USING DAMS AND RESERVOIRS TO SUPPLY MORE WATER  Large dams and reservoirs can produce cheap electricity, reduce downstream flooding, and provide year-round water for irrigating cropland, but they also displace people and disrupt aquatic systems.

22. Figure 14-13

23. Fig. 14-13a, p. 317 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

24. 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. Figure 14-15

25. The Colorado River Basin  The area drained by this basin is equal to more than one- twelfth of the land area of the lower 48 states. Figure 14-14

26. Central Arizona Project Canal  The project was designed to provide water to nearly one million acres of Indian and non- Indian irrigated agricultural land areas in Maricopa, Pinal, and Pima Counties  The CAP is a system of canals, pumping stations and storage facilities that brings water 336 miles from the Colorado River at Lake Havasu east to the Phoenix area and then south to the Tucson area. Fourteen pumping plants lift water 2,400 feet in elevation to the terminus.

28. Case Study: China’s Three Gorges Dam  There is a debate over whether the advantages of the world’s largest dam and reservoir will outweigh its disadvantages. The dam will be 2 kilometers long. The dam will be 2 kilometers long. The electric output will be that of 18 large coal- burning or nuclear power plants. The electric output will be that of 18 large coal- burning or nuclear power plants. It will facilitate ship travel reducing transportation costs. It will facilitate ship travel reducing transportation costs. Dam will displace 1.2 million people. Dam will displace 1.2 million people. Dam is built over seismatic fault and already has small cracks. Dam is built over seismatic fault and already has small cracks.

29. Dam Removal  Some dams are being removed for ecological reasons and because they have outlived their usefulness. In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S. In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S. The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams. The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams. Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment. Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.

30. TRANSFERRING WATER FROM ONE PLACE TO ANOTHER  Transferring water can make unproductive areas more productive but can cause environmental harm. Promotes investment, jobs and strong economy. Promotes investment, jobs and strong economy. It encourages unsustainable use of water in areas water is not naturally supplied. It encourages unsustainable use of water in areas water is not naturally supplied.

31. DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES  Removing salt from seawater by current methods is expensive and produces large amounts of salty wastewater that must be disposed of safely. Distillation: heating saltwater until it evaporates, leaves behind water in solid form. Distillation: heating saltwater until it evaporates, leaves behind water in solid form. Reverse osmosis: uses high pressure to force saltwater through a membrane filter. Reverse osmosis: uses high pressure to force saltwater through a membrane filter.

32. DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES  Seeding clouds with tiny particles of chemicals to increase rainfall towing icebergs or huge bags filled with freshwater to dry coastal areas have all been proposed but are unlikely to provide significant amounts of freshwater.

33. INCREASING WATER SUPPLIES BY WASTING LESS WATER  We waste about two-thirds of the water we use, but we could cut this waste to 15%. 65-70% of the water people use throughout the world is lost through evaporation, leaks, and other losses. 65-70% of the water people use throughout the world is lost through evaporation, leaks, and other losses. Water is underpriced through government subsidies. Water is underpriced through government subsidies. The lack of government subsidies for improving the efficiency of water use contributes to water waste. The lack of government subsidies for improving the efficiency of water use contributes to water waste.

34. Fig. 14-18, p. 325 Center pivot Drip irrigation Gravity flow (efficiency 60% and 80% with surge valves) Above- or below- ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river. (efficiency 90–95%) (efficiency 80%–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers.

35. TOO MUCH WATER  Heavy rainfall, rapid snowmelt, removal of vegetation, and destruction of wetlands cause flooding.  Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater.  To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.

36. TOO MUCH WATER  Comparison of St. Louis, Missouri under normal conditions (1988) and after severe flooding (1993). Figure 14-22