1. Chapter 14 Water

2. Water’s Unique Properties 1) Polar covalent molecule 2) High heat capacity (good coolant – helps to moderate climate) 3) Universal solvent 4) Expands when it freezes (helps form soil) 5) pH = 7 6) Adhesion – water sticks to other substances 7) Cohesion- water sticks to itself

3. WATER’S AVAILABILITY Only about 0.02% of the earth’s water supply is available to us as liquid freshwater (97.4 % = oceans, 2.6% = fresh)

4. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL Water stress = high demand for water (due to population), low availability Figure 14-2

5. Ground Water Terms Aquifer – underground water source (porous rock) Recharge Area – area of porous rock where water can infiltrate into the aquifer Artesian Well – crack in aquifer where water can escape Zone of Saturation – the level of water in the aquifer Zone of Aeration – distance to the water table

6. Ground Water Terms Water Table – level of water retention in the aquifer Confined Aquifer – aquifer surrounded by 2 layers of impermeable rock Unconfined Aquifer – aquifer with 1 layer of impermeable & 1 layer of permeable rock Saltwater Intrusion – when saltwater enters aquifer due to depletion of aquifer

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. WATER USAGE Irrigation: (70%) Industry: (20%) Municipal use: (10%) Average person: 1280 gallons/day.

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

10. 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

11. TOO LITTLE FRESHWATER Causes: dry climate, drought, dessication, water stress Riparian Rights (east coast) Common Law Rights (western)

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

13. Groundwater Depletion: A Growing Problem The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest).  Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S. Figure 14-8

14. Effects of Groundwater Depletion Subsidence Saltwater Intrusion Figure 14-11

15. Effects of Groundwater Depletion Subsidence Figure 14-10

16. DAMS AND RESERVOIRS Advantages: produce cheap electricity, reduce downstream flooding, and provide year-round water for irrigating cropland Disadvantages: displace people, disrupt aquatic systems, cause erosion downstream, flooding upstream, keep silt behind the dam rather than distributing it downstream, prevent fish migration

17. 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

18. Fig. 14-13b, p. 317 Powerlines Reservoir Dam Powerhouse Intake Turbine

19. The Colorado River Basin Watershed is equal to more than one-twelfth of the land area of the lower 48 states. Figure 14-14

20. China’s Three Gorges Dam –Will be 2 kilometers long. –The electric output will be that of 18 large coal- burning or nuclear power plants. –It will facilitate ship travel reducing transportation costs. –Dam will displace 1.2 million people. –Dam is built over seismatic fault and already has small cracks.

21. The California Water Project A massive transfer of water from northern California to southern California Figure 14-16

22. The Aral Sea Disaster The Aral Sea was once the world’s fourth largest freshwater lake. Figure 14-17

23. The Aral Sea Disaster Water was diverted for Irrigation Effects: –About 85% of the wetlands have been eliminated and roughly 50% of the local bird and mammal species have disappeared. –Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.

24. Options to Increase Freshwater Distillation: heating saltwater until it evaporates, leaves behind water in solid form (lots of salty waste). Reverse osmosis: uses high pressure to force saltwater through a membrane filter Cloud seeding Towing Icebergs Water Baggies

25. INCREASING WATER SUPPLIES BY WASTING LESS WATER 65-70% of the water people use throughout the world is lost through evaporation, leaks, and other losses Water is underpriced through government subsidies Drip irrigation Center-pivot, low-pressure sprinklers Xeriscaping

26. 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.

27. Using Less Water to Remove Industrial and Household Wastes Use nutrients in wastewater before treatment as soil fertilizer Use waterless and odorless composting toilets that convert human fecal matter into a small amount of soil material.

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

29. TOO MUCH WATER Human activities have contributed to flood deaths and damages. Figure 14-23

30. USING WATER MORE SUSTAINABLY Cut waste Raise water prices Preserve forests and wetlands in water basins Slow population growth. Figure 14-25