APES Study Guide 1

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Chapter 15 1. Summarize the water problems throughout the world: Water distribution is low and requires a combination of regional cooperation of allocating water supplies, slowed population growth, efficiency in water usage, higher water prices, improved irrigation, and increased grain imports 2. Explain why there is a danger of water wars: Some countries or cities will build dams that block water paths for other people (Ethiopia, Sudan, Egypt Ethiopia and Sudan block water ways to Egypt. Egypt can start war) 3. How much of the earths surface is covered by water? 71% 4. What percent of the earths water is saltwater? 97.4% Freshwater? 2.6% readily accessible fresh water? 0.014% 5. Where is the freshwater? Glaciers, ice caps, groundwaters, lakes, biota, rivers, atmospheric water vapor, soil moisture 6. Say something intelligent about the properties of water [hydrogen bonds, heat capacity, UV, freezing]: a. There are strong forces of attraction (Hydrogen bonds) between molecules of water b. Water exists as a liquid over a wide temperature range because of the strong forces of attraction between water molecules [high boiling point] c. Liquid water changes temperature slowly because it can store a large amount of heat without a large change in temperature and moderates the earths climate [large heat capacity] d. Evaporating liquid water takes large amounts of energy because of the strong forces of attraction [heat distribution and determine climate] e. Liquid water can dissolve into a variety of compound [carry dissolved nutrients, flush waste, all purpose cleaner, rove and dilute water-soluble wastes] f. Water filters out wavelengths of the suns UV radiation that would harm aquatic organisms g. Cohesive force capillary action h. Water expands [ice has low density] 7. Water saturated layers of porous underground rock are known as groundwater. 8. What is the water table? The water table is located at the top of the zone of saturation. 9. What happens to the water table during dry weather? Water table falls, and rises in wet weather 10. Distinguish the following: a. Surface runoff: the precipitation that does not infiltrate the ground, or evaporate b. Reliable runoff: Remaining 1/3 run off that we can use as

stable source of water c. Watershed/Drainage Basin: The region from which surface water drains into a river, lake, wetland, or other body of water d. Groundwater: The water stuck under porous soil and rock i. Ground water normally moves from points of high elevation and pressure to points of lower elevation and pressure: slow movement ii. Groundwater recharges slowly e. Zone of aeration/Zone of saturation/Water Table: Close to the surface is the zone of aeration, the pores of soil contain a mixture of air and some water. Lower layers of soil where the spaces are completely filled with water make up the zone of saturation. We drill shallow wells to tape into groundwater in this zone. The water table is located at the top of the zone of saturation. f. Aquifer: Deep down, porous, water-saturated layers of sand, gravel, bedrock through which groundwater flows g. Natural recharge: Replenished by precipitation that percolates downward (gravity) through soil and rock i. Lateral recharge: streams 11. Explain how the water in some aquifers can be depleted: Use faster than recharge, used up fossil aquifers that are nonrenewable, water mining 12. Distinguish between water withdrawal and consumptive water use: a. Water withdrawal: The total amount of water we remove from a river, lake, or aquifer for any purpose i. May be put back but causes thermal pollution b. Consumptive water use: Water withdrawn is not available for reuse in the basin from which it was removed due to evaporation, seepage underground, transported to another area, contamination 13. Throughout the world, the most water is used for agriculture. The greatest household use is for flushing toilets. 14. Irrigation is the biggest user of water (70%) followed by industries (20%) and cities and residences (10%) 15. Major water problems of the eastern United States include flooding, occasional urban shortages, and pollution. 16. Major water problems of the western United States include shortage of runoff, caused by low precipitation, high evaporation, and recurring prolonged drought. 17. Water scarcity during a period when precipitation is lower than normal and evaporation is higher than normal is called a drought. 18. We currently withdraw34% of the reliable surface runoff and

in 2025 we will withdraw more than 70%. 19. List four causes of water scarcity: a. Dry climate, drought, desiccation (drying of exposed soil because of deforestation and overgrazing), and water stress (low per capita availability of water) b. A country is water stressed when the volume of reliable runoff per person drops below 1,700 cubic meters per year (water withdrawal 20% higher). A country suffers from water scarcity when per capita water availability falls below 1,000 cubic meters per year. c. 41% of the worlds population lives in river basins located in 20 countries that suffer from water stress or water scarcity. 40 countries by 2020, 60 countries in 2050. 20. Identify ways that water supply can be increased (six ways): a. Build dams and reservoirs b. Bring in surface water from another area c. Withdraw groundwater d. Convert salt water to freshwater (desalination) e. Reduce water waste f. Import food to reduce water use g. Raising livestock 21. Discuss the controversy over whether freshwater resources should be owned and managed by governments or by private corporations: a. Private companies have the money and expertise to manage these resources better than government bureaucracies b. Governments hiring private companies to manage water resources must set standards and maintain strict oversight of such contracts c. Water is a public resource d. Once water is owned by foreign-based corporation, efforts to return the systems to public control can lead to severe economic penalties under World Trade Organization e. Private companies make money by delivering water, and have more incentive to sell as much water than conserve f. Lack of money to pay water bills, the poor will be left out 22. Dams a. Pros: i. Reservoir is useful for recreation and fishing ii. Can produce cheap electricity iii. Downstream flooding is reduced iv. Provides water for year-round irrigation b. Cons: i. Large losses of water through evaporation ii. Flooded land destroys forests or cropland and

displaces people iii. Migration and spawning of some fish are disrupted iv. Downstream cropland and estuaries are deprived of nutrient-rich silt c. The more large dams built, the more annual reliable runoff increased for humans. However it can reduce downstream flow to a trickle and prevent it from reaching the sea as a part of the hydrologic cycle. d. Colorado River Basin Las Vegas (Nevada), San Diego (California), Imperial Valley (California), Mexico i. Pros: 1. Provides hydroelectricity plants 2. Water for more than 25 million people in 7 states 3. Water used to grow about 15% of the nations produce and livestock 4. Supports a multibillion-dollar recreation industry ii. Cons: 1. Includes driest lands in the United States and Mexico 2. Legal pacts in 1922 and 1944 allocated more water for human use than the river can supply 3. Pact also allocated no water for environmental purposes 4. Withdrawals of water prevented river to go to Gulf of California which threatens the survival of species that spawn in the river e. Chinas Three Gorges Dam i. Pros: 1. Will generate about 10% of electricity 2. Reduce dependence on coal 3. Reduces air pollution 4. Reduces CO2 emissions 5. Reduces chances of downstream flooding for 15 million people 6. Reduces river silting below dam by eroded soil 7. Increases irrigation water for croplands ii. Cons: 1. Floods large areas of croplands 2. Displaces 1.9 million people 3. Increases water pollution because of reduced water flow 4. Reduces deposits of nutrient-rich sediments below the dam 5. Increases saltwater introduced into drinking water near mouth of river because of decreased

water flow 6. Disrupts spawning and migration of fish 7. High cost 23. How do dams relate to a. Soil Fertility: Downstream croplands are deprived of silt b. Air Pollution: Generates electricity, reduces need for energy by coal, reduces air pollution c. Flooding: Downstream flooding is reduced, but will flood lands and displace people upstream d. Farming: Regulates irrigation for cropland, but prevents silt to run downstream 24. Describe the cause and effects of the Aral Sea water transfer project in central Asia: It is a result of a large-scale water transfer project in an area of the former Soviet Union with the driest climate in central Asia. The water transfer was used to create irrigated areas for cotton and rice. This projected, coupled with droughts and high evaporation rates has caused a regional ecological, economic, and health disaster. The seas salinity has tripled. 25. Describe the controversy over: a. California Water Transfer Project i. Sending more water south would degrade the Sacramento River, threaten fisheries, and reduce the flushing action that helps clean San Francisco Bay of pollutants. b. James Bay Water Transfer Project i. Flood an area of boreal forests and tundra. It will displace thousands of indigenous Cree and Inuit, who have lived off of James Bay by subsistence hunting, fishing, and trapping. 26. List the advantages and disadvantages of supplying more water by withdrawing groundwater. Explain why excessive groundwater withdrawal can be viewed as an example of the tragedy of the commons. What is saltwater intrusion, where does it occur, and what harm does it cause? a. Pros: i. Aquifers are widely available and are renewable sources of water as long as the water is not withdrawn faster than it is replaced and as long as the aquifers arent contaminated