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Chapter 14 Water. Core Case Study: Water Conflicts in the Middle East - A Preview of the Future Many countries in the Middle East, which has one of the.

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Presentation on theme: "Chapter 14 Water. Core Case Study: Water Conflicts in the Middle East - A Preview of the Future Many countries in the Middle East, which has one of the."— Presentation transcript:

1 Chapter 14 Water

2 Core Case Study: Water Conflicts in the Middle East - A Preview of the Future Many countries in the Middle East, which has one of the worlds highest population growth rates, face water shortages. Many countries in the Middle East, which has one of the worlds highest population growth rates, face water shortages. Figure 14-1

3 Water Conflicts in the Middle East: A Preview of the Future Most water in this dry region comes from the Nile, Jordan or Tigris rivers. Most water in this dry region comes from the Nile, Jordan or Tigris rivers. Countries upstream are building dams and drawing more water…leaving little for downstream countries Countries upstream are building dams and drawing more water…leaving little for downstream countries Countries are in disagreement as to who has water rights. Countries are in disagreement as to who has water rights. War could easily erupt in this volatile part of the world War could easily erupt in this volatile part of the world

4 Water Conflicts in the Middle East: A Preview of the Future Currently, there are no cooperative agreements for use of 158 of the worlds 263 water basins that are shared by two or more countries. Currently, there are no cooperative agreements for use of 158 of the worlds 263 water basins that are shared by two or more countries. Emerging water shortages in many parts of the world – one of the most serious environmental problems Emerging water shortages in many parts of the world – one of the most serious environmental problems

5 WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL Necessary for life Necessary for life Moderates climate, Moderates climate, Sculpts the land, Sculpts the land, Removes and dilutes wastes and pollutants, Removes and dilutes wastes and pollutants, Moves continually through the hydrologic cycle. Moves continually through the hydrologic cycle. Only about 0.02% of the earths water supply is available to us as liquid freshwater. Only about 0.02% of the earths water supply is available to us as liquid freshwater.

6 Water One of our most poorly managed resource One of our most poorly managed resource We waste & pollute it We waste & pollute it No substitute No substitute Lack of safe water & sanitation is leading cause of illness in world Lack of safe water & sanitation is leading cause of illness in world Water quality is worsening Water quality is worsening

7 Water By The Numbers Oceans: 97% Oceans: 97% Glaciers / polar ices caps: 1.8% Glaciers / polar ices caps: 1.8% Groundwater: 0.9% Groundwater: 0.9% Other land surface water (rivers, lakes): 0.017% Other land surface water (rivers, lakes): 0.017% 20% of all surface freshwater is in Lake Baikal, Russia. 20% of all surface freshwater is in Lake Baikal, Russia. The Ogallala Aquifer is the largest groundwater reserve. The Ogallala Aquifer is the largest groundwater reserve. The Middle East has the lowest amount of naturally available freshwater and uses desalination for their water supply. The Middle East has the lowest amount of naturally available freshwater and uses desalination for their water supply. Lake Bikal is the most voluminous freshwater lake in the world. The Ogallala Aquifer is located in the central plains of the US because of watershed properties

8 Fresh Water Resources Most of the 71% of Earths water, more than 1.3 billion cubic kilometers, is contained in the oceans. Only 35 million cubic kilometers is fresh water. Most of the 71% of Earths water, more than 1.3 billion cubic kilometers, is contained in the oceans. Only 35 million cubic kilometers is fresh water. Only a tiny amount of the water on Earth is accessible and usable to humans because the ice caps/sheets/ glaciers are the majority of freshwater and are not readily available for use. Only a tiny amount of the water on Earth is accessible and usable to humans because the ice caps/sheets/ glaciers are the majority of freshwater and are not readily available for use. Earths total water Seawater 97 % Fresh water 3% Fresh water Surface water 0.3% Ice caps and glaciers 77.2% Ground water 22.46% Atmospheric water 0.04% Lakes 87% Swamps 11% Rivers 2% Surface water

9 Surface Water Examples – streams, rivers, and lakes Examples – streams, rivers, and lakes Source – precipitation Source – precipitation Watershed – Ex. small streams larger streams rivers sea Watershed – Ex. small streams larger streams rivers sea

10 Groundwater Aquifers–porous rock w/ water flowing through Aquifers–porous rock w/ water flowing through Water Table – the level of earths land crust to which the aquifer is filled Water Table – the level of earths land crust to which the aquifer is filled Renewability – the circulation rate of groundwater is slow (300 to 4,600 years). Renewability – the circulation rate of groundwater is slow (300 to 4,600 years).

11 Water Usage Agriculture – watering crops Agriculture – watering crops Industry – coolant (power plant) Industry – coolant (power plant) Domestic and Municipal – drinking, sewage, bathwater, dishwater & laundry Domestic and Municipal – drinking, sewage, bathwater, dishwater & laundry

12 Humans intervene in the water cycle by utilizing the resource for their own needs. Humans intervene in the water cycle by utilizing the resource for their own needs. Water is used for consumption, municipal use, in agriculture, in power generation, and for industrial manufacturing. Water is used for consumption, municipal use, in agriculture, in power generation, and for industrial manufacturing. Industry is the greatest withdrawer of water but some of this is returned. Agriculture is the greatest water consumer. Industry is the greatest withdrawer of water but some of this is returned. Agriculture is the greatest water consumer. Using water often results in its contamination. The supply of potable (drinkable) water is one of the most pressing of the worlds problems. Using water often results in its contamination. The supply of potable (drinkable) water is one of the most pressing of the worlds problems. The Demand for Water Hydroelectric power generation… Irrigation… Washing, drinking, bathing…

13 Potable Water Potable water (water suitable to drink) is a rare commodity in large parts of the world. Potable water (water suitable to drink) is a rare commodity in large parts of the world. Access to potable water is limited by: Access to potable water is limited by: ease of distribution, level of water treatment (e.g. sanitation), & amount of available water resources (eg rivers) Countries must deal with problems of removing water borne diseases and dissolved toxins. Countries must deal with problems of removing water borne diseases and dissolved toxins. Once treated, distribution and storage of water becomes important. Once treated, distribution and storage of water becomes important. In many countries, distribution of water is difficult and storage of large amounts almost impossible. In many countries, distribution of water is difficult and storage of large amounts almost impossible. Photo: Bob Metcalf Water in many developing nations is difficult to come by, and treatment may be nonexistent. In developed nations, potable water is abundant and treatment is regulated.

14 Comparison of population sizes and shares of the worlds freshwater among the continents. Figure 14-2

15 Global Water Reserves Ogallala Aquifer A vast water-table aquifer located beneath the Great Plains in the US. It is extensively used for irrigation. At current usage rates it may be depleted by Mississippi River Drains most of the area between the Rocky Mountains and the Appalachians. A series of locks and dams provide for barge traffic. Amazon River Accounts for 20% of the world's total river flow and drains 40% of South America. Brazil has the largest supply of freshwater in the world. North American Great Lakes The largest group of freshwater lakes on Earth, containing 22% of the world's fresh surface water.

16 Global Water Reserves Volga River With its many tributaries, drains an area of about 1.35 million km 2 in the most heavily populated part of Russia. High levels of chemical pollution currently give cause for environmental concern. Yangtze River Flows 6300 km East China Sea. The Yangtze is subject to extensive flooding, which is only partly controlled by the Three Gorges Dam. It is also heavily polluted. Congo River Is the largest river in Western Central Africa with the second- largest flow in the world. It drains an extensive area of rainforest. Murray-Darling Basin Drains one-seventh of the Australian land mass. Over 70% of Australia's irrigation resources are concentrated there. Ganges Basin Central to the agricultural economy of India. A recent UN report indicates the glaciers feeding the Ganges may disappear by 2030, leaving it as a seasonal system fed by the monsoon rains. Lake Baikal Is the second most voluminous lake in the world. Contains 20% of the worlds freshwater

17 Fresh Water Use Intensive agriculture uses large amounts of water, 69% of the freshwater. Intensive agriculture uses large amounts of water, 69% of the freshwater. Improved irrigation techniques can reduce the amount required. Every year huge quantities of water as transported to irrigate crops. Industrial water use increases along with the human population, using about 22% of freshwater. Industrial water use increases along with the human population, using about 22% of freshwater. The cooling of power plants and the processing of almost all commercial goods requires the use the water. Manufacturing and production processes are usually water intensive. Some everyday items use surprisingly large amounts of water in their production. Industrial treatment uses 22% Irrigation accounts for 69% An automobile: 380,000 liters of water

18 Municipal Water Use Cities and residences use only 8% of the freshwater. Nearly half of the municipal water in the US is used to flush toilets or water lawns. Cities and residences use only 8% of the freshwater. Nearly half of the municipal water in the US is used to flush toilets or water lawns. Another 20-35% is lost in water leaks. Large savings can be made by improving the efficiency of water use. Treatment of waste water is a major issue. 454 g of grain-fed beef: 3,000 liters of water The cotton in a pair of jeans: 6,800 liters of water Municipal supply is about 8%

19 Industrial Water Use Cubic meters per person per year Agricultural Water Use Cubic meters per person per year Domestic Water Use Cubic meters per person per year Water Use: America Source: Worldwater.org

20 Domestic Water Use Agricultural Water Use Industrial Water Use Cubic meters per person per year Water Use: Africa Source: Worldwater.org

21 Industrial Water Use Cubic meters per person per year Agricultural Water Use Cubic meters per person per year Domestic Water Use Cubic meters per person per year Water Use: Asia Source: Worldwater.org

22 Domestic Water Use Agricultural Water Use Industrial Water Use Cubic meters per person per year Water Use: Europe Source: Worldwater.org

23 Agricultural Water Use Industrial Water Use Cubic meters per person per year Domestic Water Use Source: Worldwater.org Cubic meters per person per year Water Use: Oceania

24 WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL Some precipitation infiltrates the ground and is stored in soil and rock (groundwater). 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. 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.

25 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

26 WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL We currently use more than half of the worlds reliable runoff of surface water and could be using 70-90% by We currently use more than half of the worlds reliable runoff of surface water and could be using 70-90% by About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources. 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%).

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

28 Fig. 14-4a, p. 309 Average annual precipitation (centimeters) More than 122 Less than 4181–122 41–81

29 Fig. 14-4b, p. 309 Acute shortage Metropolitan regions with population greater than 1 million Shortage Adequate supply

30 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. 17 western states by 2025 could face intense conflict over scarce water needed for urban growth, irrigation, recreation and wildlife. Figure 14-5

31 Fig. 14-5, p. 310 Wash. Montana Oregon N.D. Idaho Wyoming S.D. NevadaNeb. Utah Colo. Kansas California Oak. N.M. Texas Highly likely conflict potential Moderate conflict potential Unmet rural water needs Substantial conflict potential

32 TOO LITTLE FRESHWATER About 41% of the worlds population lives in river basins that do not have enough freshwater. About 41% of the worlds population lives in river basins that do not have enough freshwater. Many parts of the world are experiencing: Many parts of the world are experiencing: Rivers running dry. Rivers running dry. Lakes and seas shrinking. Lakes and seas shrinking. Falling water tables from overpumped aquifers. Falling water tables from overpumped aquifers.

33 Stress on the Worlds River Basins Comparison of the amount of water available with the amount used by humans. Comparison of the amount of water available with the amount used by humans. Figure 14-6

34 Case Study: Who Should Own and Manage Freshwater Resources There is controversy over whether water supplies should be owned and managed by governments or by private corporations. There is controversy over whether water supplies should be owned and managed by governments or by private corporations. European-based water companies aim to control 70% of the U.S. water supply by buying up water companies and entering into agreements with cities to manage water supplies. European-based water companies aim to control 70% of the U.S. water supply by buying up water companies and entering into agreements with cities to manage water supplies.

35 TOO LITTLE FRESHWATER Cities are outbidding farmers for water supplies from rivers and aquifers. Cities are outbidding farmers for water supplies from rivers and aquifers. Countries are importing grain as a way to reduce their water use. Countries are importing grain as a way to reduce their water use. More crops are being used to produce biofuels. More crops are being used to produce biofuels. Our water options are: 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.

36 WITHDRAWING GROUNDWATER TO INCREASE SUPPLIES Most aquifers are renewable resources unless water is removed faster than it is replenished or if they are contaminated. 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. 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.

37 Fig. 14-7, p. 313 Trade-Offs Withdrawing Groundwater AdvantagesDisadvantages Useful for drinking and irrigation Aquifer depletion from overpumping Available year- round Sinking of land (subsidence) from overpumping Exists almost everywhere Polluted aquifers for decades or centuries Renewable if not overpumped or contaminated Saltwater intrusion into drinking water supplies near coastal areas Reduced water flows into surface waters No evaporation losses Cheaper to extract than most surface waters Increased cost and contamination from deeper wells

38 Human Effects Most water used by humans comes from rivers, lakes, & aquifers. Most water used by humans comes from rivers, lakes, & aquifers. Damming rivers for electricity affects water flow downstream as seen in the James Bay project in Quebec with over 600 dams blocking 19 rivers. Damming rivers for electricity affects water flow downstream as seen in the James Bay project in Quebec with over 600 dams blocking 19 rivers. Irrigation and diversions for drinking water displace vast amounts of the water for these resource stores. Irrigation and diversions for drinking water displace vast amounts of the water for these resource stores. Pollution from fertilizers, waste, an sewage can have paralyzing effects on rivers, lakes, and oceans. Pollution from fertilizers, waste, an sewage can have paralyzing effects on rivers, lakes, and oceans. These actions can have dramatic effects on the habitats and can cause loss of biodiversity. These actions can have dramatic effects on the habitats and can cause loss of biodiversity. Irrigation can move move millions of liters of water from rivers and aquifers, affecting land down stream. Damming and diverting rivers lowers the availability of water downstream and stops annual floods that replace soil nutrients. Dams, locks and other obstacles make it very difficult for migratory fish to find their way to breeding grounds.

39 Rivers as Highways The major rivers of the worlds provide water for irrigation and drinking and enable the transport of large amounts of freight especially when dammed. The major rivers of the worlds provide water for irrigation and drinking and enable the transport of large amounts of freight especially when dammed. Huge barges moved by tugboats are used on many rivers and lakes of developed countries. Huge barges moved by tugboats are used on many rivers and lakes of developed countries. However there are many negative environmental effects. However there are many negative environmental effects. Some rivers such as the Yangtze are so polluted and congested with ships that little can live in them. Some rivers such as the Yangtze are so polluted and congested with ships that little can live in them. The Yangtze River Dolphin was last seen in 2002 and has since been declared functionally extinct. It is the first cetacean extinction directly attributable to human interference. Mississippi River, USA Yangtze River, China Photo: Ryu Cheoi Creative Commons Attribution ShareAlike 3.0Creative Commons Attribution ShareAlike 3.0

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

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

42 Fig , p. 315 Major irrigation well Well contaminated with saltwater Water table Fresh groundwater aquifer Sea level Saltwater Interface Seafloor Saltwater intrusion Interface Normal interface

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

44 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. Irrigation systems from the nonrenewable aquifer appear as green dots. Brown dots are wells that have gone dry. Figure 14-9

45 Fig , p. 316 Solutions Groundwater Depletion PreventionControl Waste less water Raise price of water to discourage waste Subsidize water conservation Ban new wells in aquifers near surface waters Tax water pumped from wells near surface waters Buy and retire groundwater withdrawal rights in critical areas Do not grow water- intensive crops in dry areas Set and enforce minimum stream flow levels

46 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. 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.

47 Dams and Reservoirs Benefits: Hydroelectric power; provides water to towns; recreation; controls floods downstreamBenefits: Hydroelectric power; provides water to towns; recreation; controls floods downstream Problems: Reduces downstream flow; prevents water from reaching the sea (Colorado River) devastates fish life; reduces biodiversity. Problems: Reduces downstream flow; prevents water from reaching the sea (Colorado River) devastates fish life; reduces biodiversity.

48 Figure 14-13

49 Fig a, 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

50 Fig b, p. 317 Powerlines Reservoir Dam Powerhouse Intake Turbine

51 Case Study: The Colorado Basin – an Overtapped Resource The Colorado River has so many dams and withdrawals that it often does not reach the ocean. The Colorado River has so many dams and withdrawals that it often does not reach the ocean. 14 major dams and reservoirs, and canals. 14 major dams and reservoirs, and canals. Water is mostly used in desert area of the U.S. Water is mostly used in desert area of the U.S. Provides electricity from hydroelectric plants for 30 million people (1/10 th of the U.S. population). Provides electricity from hydroelectric plants for 30 million people (1/10 th of the U.S. population).

52 Case Study: The Colorado Basin – an Overtapped Resource Lake Powell, is the second largest reservoir in the U.S. Lake Powell, is the second largest reservoir in the U.S. It hosts one of the hydroelectric plants located on the Colorado River. It hosts one of the hydroelectric plants located on the Colorado River. Figure 14-15

53 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. 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

54 Case Study: Chinas Three Gorges Dam There is a debate over whether the advantages of the worlds largest dam and reservoir will outweigh its disadvantages. There is a debate over whether the advantages of the worlds 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.

55 Three Gorges Dam The Three Gorges Dam spans the Yangtze River at Sandouping, China, and is the largest hydroelectric dam in the world, capable of producing 22,500MW of electricity. The Three Gorges Dam spans the Yangtze River at Sandouping, China, and is the largest hydroelectric dam in the world, capable of producing 22,500MW of electricity. Major construction began in 1994 and is expected to be fully completed by Major construction began in 1994 and is expected to be fully completed by Photo: Christoph FlinkoBl Creative Commons Attribution ShareAlike 3.0 Creative Commons Attribution ShareAlike 3.0 Photo: Guuganji Creative Commons Attribution ShareAlike 3.0Creative Commons Attribution ShareAlike 3.0

56 Filling the Dam The reservoir behind the Three Gorges Dam extends 600km upstream. The dam itself is over 2km wide and 186m high. The reservoir behind the Three Gorges Dam extends 600km upstream. The dam itself is over 2km wide and 186m high. Satellite image of Three Gorges Dam 1987, before construction. Image: NASA

57 Filling the Dam Satellite image of Three Gorges Dam 2000 Image: NASA

58 Filling the Dam Satellite image of Three Gorges Dam 2004 Image: NASA

59 Satellite image of Three Gorges Dam 2006 Filling the Dam Image: NASA

60 Dam Removal Some dams are being removed for ecological reasons and because they have outlived their usefulness. 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.

61 TRANSFERRING WATER FROM ONE PLACE TO ANOTHER Transferring water can make unproductive areas more productive but can cause environmental harm. 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.

62 Case Study: The California Experience A massive transfer of water from water-rich northern California to water-poor southern California is controversial. A massive transfer of water from water-rich northern California to water-poor southern California is controversial. Figure 14-16

63 Case Study: The Aral Sea Disaster The Aral Sea was once the worlds fourth largest freshwater lake. The Aral Sea was once the worlds fourth largest freshwater lake. Figure 14-17

64 Case Study: The Aral Sea Disaster Diverting water from the Aral Sea and its two feeder rivers mostly for irrigation has created a major ecological, economic, and health disaster. Diverting water from the Aral Sea and its two feeder rivers mostly for irrigation has created a major ecological, economic, and health disaster. About 85% of the wetlands have been eliminated and roughly 50% of the local bird and mammal species have disappeared. About 85% of the wetlands have been eliminated and roughly 50% of the local bird and mammal species have disappeared. Since 1961, the seas salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct. Since 1961, the seas salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.

65 Aswan High Dam Two dams straddle the Nile River at Aswan, Egypt. The Aswan High Dam was completed in 1970 and formed Lake Nasser. which is 550 km long and capable of holding two years of the Nile's annual flow. Two dams straddle the Nile River at Aswan, Egypt. The Aswan High Dam was completed in 1970 and formed Lake Nasser. which is 550 km long and capable of holding two years of the Nile's annual flow. The main objectives of the project were: The main objectives of the project were: energy generation in a renewable form. flood control in downstream locations. provision of water for agriculture and domestic use. A serious detrimental effect is the loss of the annual floods downstream. These used to replenish the nutrients of the flood plain and flush out accumulated salts. A serious detrimental effect is the loss of the annual floods downstream. These used to replenish the nutrients of the flood plain and flush out accumulated salts. Wiki Commons

66 Aswan High Dam Photo: NASA Without flooding, fertilizers must be applied to the land and salts build up in the soils, causing crops to fail. Without annual deposition of river sediments because of build- up behind the dam, the land is eroding, allowing the sea to encroach up the river delta. Damming has also caused 64% of commercially fished species in the Nile to disappear. Time will tell if better management will help to reverse the problems currently being experienced in the Nile Delta region.

67 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. 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.

68 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. 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.

69 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%. We waste about two-thirds of the water we use, but we could cut this waste to 15% % of the water people use throughout the world is lost through evaporation, leaks, and other losses % 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.

70 Water Conservation Strategies Irrigation techniques: Irrigation techniques: Employ micro/drip irrigation Irrigate at times of less low evaporation (eg. Night) Choose crops that do not require irrigation in certain climates Agricultural & other methods: Agricultural & other methods: Incorporate shelterbelts or windbreaks Reduce runoff by contour planting, strip cropping, and terracing Cover surface with mulch to prevent evaporation Eat less meat Center pivot (above) and gravity flow (below) are not as efficient as drip irrigation that allows water to trickle to the roots.

71 INCREASING WATER SUPPLIES BY WASTING LESS WATER Sixty percent of the worlds irrigation water is currently wasted, but improved irrigation techniques could cut this waste to 5-20%. Sixty percent of the worlds irrigation water is currently wasted, but improved irrigation techniques could cut this waste to 5-20%. Center-pivot, low pressure sprinklers sprays water directly onto crop. Center-pivot, low pressure sprinklers sprays water directly onto crop. It allows 80% of water to reach crop. It allows 80% of water to reach crop. Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%. Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%. Drip Irrigation is the most efficient method Drip Irrigation is the most efficient method

72 Fig , 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.

73 Fig , p. 326 Solutions Reducing Irrigation Water Waste Line canals bringing water to irrigation ditches Level fields with lasers Irrigate at night to reduce evaporation Monitor soil moisture to add water only when necessary Polyculture Organic farming Don't grow water-thirsty crops in dry areas Grow water-efficient crops using drought resistant and salt-tolerant crop varieties Irrigate with treated urban waste water Import water-intensive crops and meat

74 Solutions: Getting More Water for Irrigation in Developing Countries – The Low-Tech Approach Many poor farmers in developing countries use low-tech methods to pump groundwater and make more efficient use of rainfall. Many poor farmers in developing countries use low-tech methods to pump groundwater and make more efficient use of rainfall. Figure 14-20

75 Fig , p. 327 Solutions Reducing Water Waste Redesign manufacturing processes Repair leaking underground pipes Landscape yards with plants that require little water Use drip irrigation Fix water leaks Use water meters Raise water prices Use waterless composting toilets Require water conservation in water- short cities Use water-saving toilets, showerheads, and front loading clothes washers Collect and reuse household water to irrigate lawns and nonedible plants Purify and reuse water for houses, apartments, and office buildings Don't waste energy

76 Raising the Price of Water: A Key to Water Conservation We can reduce water use and waste by raising the price of water while providing low lifeline rates for the poor. We can reduce water use and waste by raising the price of water while providing low lifeline rates for the poor. When Boulder, Colorado introduced water meters, water use per person dropped by 40%. When Boulder, Colorado introduced water meters, water use per person dropped by 40%. A 10% increase in water prices cuts domestic water use by 3-7%. A 10% increase in water prices cuts domestic water use by 3-7%.

77 Solutions: Using Less Water to Remove Industrial and Household Wastes We can mimic the way nature deals with wastes instead of using large amounts of high-quality water to wash away and dilute industrial and animal wastes. We can mimic the way nature deals with wastes instead of using large amounts of high-quality water to wash away and dilute industrial and animal wastes. Use nutrients in wastewater before treatment as soil fertilizer. 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. Use waterless and odorless composting toilets that convert human fecal matter into a small amount of soil material.

78 TOO MUCH WATER Heavy rainfall, rapid snowmelt, removal of vegetation, and destruction of wetlands cause flooding. 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. 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. To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.

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

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

81 Fig a, p. 330 Oxygen released by vegetation Diverse ecological habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Agricultural land Steady river flow Leaf litter improves soil fertility Tree roots stabilize soil and aid water flow Vegetation releases water slowly and reduces flooding Forested Hillside

82 Fig b, p. 330 Tree plantation Roads destabilize hillsides Evapotranspiration decreases Ranching accelerates soil erosion by water and wind Winds remove fragile topsoil Agricultural land is flooded and silted up Gullies and landslides Heavy rain leaches nutrients from soil and erodes topsoil Silt from erosion blocks rivers and reservoirs and causes flooding downstream Rapid runoff causes flooding After Deforestation

83 Fig , p. 331 Solutions Reducing Flood Damage PreventionControl Preserve forests on watersheds Strengthen and deepen streams (channelization) Preserve and restore wetlands in floodplains Tax all development on floodplains Build levees or floodwalls along streams Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry, and recreation Build dams

84 SOLUTIONS: USING WATER MORE SUSTAINABLY We can use water more sustainably by cutting waste, raising water prices, preserving forests and wetlands in water basins, and slowing population growth. We can use water more sustainably by cutting waste, raising water prices, preserving forests and wetlands in water basins, and slowing population growth. Figure 14-25

85 Fig , p. 333 What Can You Do? Water Use and Waste Use water-saving toilets, showerheads, and faucet aerators. Shower instead of taking baths, and take short showers. Stop water leaks. Turn off sink faucets while brushing teeth, shaving, or washing. Flush toilets only when necessary. Wash only full loads of clothes or use the lowest water-level for smaller loads. Use recycled (gray) water for lawn, gardens, house plants, car washing. Wash a car from a bucket of soapy water, and use the hose for rinsing only. If you use a commercial car wash, try to find one that recycles its water. Replace your lawn with native plants that need little if any watering and decorative gravel or rocks. Water lawns and gardens in the early morning or evening. Sweep or blow off driveways instead of hosing off with water. Use drip irrigation and mulch for gardens and flowerbeds.


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