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13-4 Is Transferring Water from One Place to Another the Answer?
Concept Transferring water from one place to another has greatly increased water supplies in some areas, but it has also disrupted ecosystems.
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Water Transfers Can Be Wasteful and Environmentally Harmful
Using a lot of water to produce a water thirsty plant, like ________________, is not necessarily a bad thing…if the crop is grown in areas with ___________ of water However, U.S. lettuce primarily comes from California’s _____________ Central Valley area, and requires the use of heavy _________________ lettuce a lot arid irrigation
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Southern California Lettuce Grown with ________________ California Water
Northern Figure 13.15: This lettuce crop is growing in the Imperial Valley of central California. This and other water-intensive crops are grown in this arid area mostly because of the availability of cheap, government-subsidized irrigation water brought in from northern California, but also because the weather allows for growing crops year round in this valley. Question: Have you ever checked to see where your lettuce and other produce that you eat come from? Fig , p. 331
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California Transfers Water from Water-Rich Areas to Water-Poor Areas
Water ________________ from north to south by Tunnels Aqueducts Underground pipes This water transfer project is called the ___________________ ___________ ___________ ___________________ water use in arid regions Environmental damage to _______________ River and San Francisco ___________ transferred California Water Project Inefficient Sacramento Bay
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Colorado River Aqueduct Central Arizona Project
CALIFORNIA NEVADA Shasta Lake Oroville Dam and UTAH Sacramento River Reservoir Feather River North Bay Aqueduct Lake Tahoe Sacramento SIERRA MOUNTAIN RANGE San Francisco South Bay Aqueduct Hoover Dam and Reservoir (Lake Mead) Fresno San Luis Dam and Reservoir San Joaquin Valley Colorado River Los Angeles Aqueduct California Aqueduct ARIZONA Colorado River Aqueduct Santa Barbara Figure 13.16: The California Water Project and the Central Arizona Project transfer huge volumes of water from one watershed to another. The red arrows show the general direction of water flow. Questions: What effects might this system have on different areas on this map? How might it affect areas from which the water is taken? Central Arizona Project Los Angeles Phoenix Salton Sea San Diego Tucson MEXICO Fig , p. 331
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California Transfers Water from Water-Rich Areas to Water-Poor Areas
Projected climate change may make situation worse… snow packs in the _________ ______________ mountains may… melt _________________ Receive ___________ precipitation during drought years Some analysts project that during this century, many people living in arid, Southern California cities, will have to _______________ elsewhere High Sierra faster less move
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Case Study: The Aral Sea Disaster (1)
The ___________ Sea was once the world’s _______ largest lake 1960: has been used for a large scale water transfer to irrigate one of the driest areas in central _____________ Cotton and rice Aral 4th Asia
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Natural Capital Degradation: The Aral Sea, Shrinking Freshwater Lake
Figure 13.17: Natural capital degradation. The Aral Sea was one of the world’s largest saline lakes. Since 1960, it has been shrinking and getting saltier because most of the water from the two rivers that replenish it has been diverted to grow cotton and food crops. These satellite photos show the sea in 1976 and in As the Southern Aral Sea shrank, it split into two lakes and left behind a salty desert, economic ruin, increasing health problems, and severe ecological disruption. By late 2009, the larger eastern part of the once huge Southern Aral Sea was gone (bottom-right part of each photo). The smaller Northern Aral Sea (top of each photo) has also shrunk, but not nearly as much as the Southern Aral Sea has. Question: What are three things that you think should be done to help prevent further shrinkage of the Aral Sea? Fig , p. 332
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Case Study: The Aral Sea Disaster (2)
The large scale water transfer was also coupled with… _____________________ High ________________ rates Since 1961… Water levels have dropped by an amount equivalent to a _____________ building the sea’s salinity (___________ content) has risen _________________________ drought evaporation 6-story salt seven-fold
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Case Study: The Aral Sea Disaster (2)
85% of the area’s ________________ have been eliminated ___________ of local bird and mammal species have disappeared Devastated the area’s ______________ industry The southern portion of the Aral Sea is now a desert covered with glistening white _______________ wetlands Half fishing salt
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Case Study: The Aral Sea Disaster (2)
Wind-blown salt and dust ________________ other fields and wildlife areas Settling on the __________________ in the Himalayas causing them to melt at a ____________ rate To increase yields, farmers are using _________ herbicides, insecticides, and fertilizers, which have percolated into the ___________________ pollutes glaciers faster more groundwater
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Case Study: The Aral Sea Disaster (2)
People living in the Aral Sea watershed have experienced increasing ___________ problems due to all of the pollution Anemia Respiratory illnesses Liver and kidney disease Eye problems Various cancers health
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Case Study: The Aral Sea Disaster (2)
Since 1999, the United Nations and World Bank have spent about $600 million to… _________________ drinking water _______________ irrigation and drainage systems Neighboring countries have been replacing water-thirsty crops with others that require ________ irrigation ___________ was built to raise lake levels in the Northern Aral Sea purify improve less Dike
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13-5 Is Converting Salty Seawater to Freshwater the Answer?
Concept 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.
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Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (1)
Desalination - removing dissolved salts from ocean water or from _____________ (slightly salty) water in aquifers or lakes Two most widely used methods are ________________ and _______________ osmosis Distillation uses… heat to evaporate water, leaving salts ______________ Cool or ___________________ steam back into liquid water brackish distillation reverse behind condense
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Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (1)
Reverse osmosis…also called _________________ Uses high ______________ to force salt water through a membrane _____________ with pores that are small enough to remove the salt Currently there are about ________________ desalination plants mostly in arid areas of… Middle east North Africa Caribbean Mediterranean microfiltration pressure filter 14,450
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Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (2)
Three major problems with the widespread use of desalination High __________ and energy footprint Chemicals are required to keep down ___________ growth…____________ many marine organisms Produces huge quantities of ____________ salts that must go somewhere Bottom Line: Currently, desalination is practical only for water _____________, _______________ countries cost algal kill waste short wealthy
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Science Focus: The Search for Improved Desalination Technology
Using other forms of energy to power plants… _____________________ Using ___________ to carry desalination equipment instead of land-based desalination plants Use water from depths ______________ where most marine organisms live The remaining salt or _____________ could be carried away from the coast and ___________________ solar wind ocean waves ships below brine diluted
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Review Questions What are some disadvantages of transferring water?
What are some disadvantages of using desalination methods? inefficient Dries other areas (ecological damage) Pollution High cost High energy needs Chemical use and salt waste
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