Chapter 11 study guide – Flashcards with Answers

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The world’s fresh water supply is continously collected, purified, recycled, and distributed in the
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Hydrologic cycle
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List the reasons that water is important
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Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and is recycled by the hydrologic cycle
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Define watershed
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the region from which surface water drains into a river, lake, wetland, or other body of water
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Water covers about _____ % of the earth’s surface
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71
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Why is water important
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Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and is recycled by the hydrologic cycle
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How do we value and handle our water?
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One of our most poorly managed resources. We waste it and pollute it. We also charge too little for making it available
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Approximately ___% of the earth’s water is fresh rather than salt water
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2.6
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The hydrologic cycle will naturally purify and recycle fresh water as long as humans don’t
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Overload water systems with slowly degradable and non-degradable wastes or withdraw water from underground supplies faster than it is replenished
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Define aquifers
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Porous, water-saturated layers of sand, gravel, or bedrock through which groundwater flows
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Averaged globally, about two-thirds of the water withdrawn each year is used for
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To irrigate 1/5 of the world’s cropland
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The zone of saturation is
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List categories of water pollutant
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List ways to increase water supply
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Building dams, bringing water from somewhere else
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Advantage of large dams and reservoirs
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Large dams and reservoirs can produce cheap electricity, reduce downstream flooding and provide year-round water for irrigating cropland
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What are the disadvantages of large dams
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Large losses of water through evaporation, flooded land destroys forest or cropland and displaces people, migration and spawning of some fish are disrupted, down stream cropland and estuaries are deprived of nutrient rich silt
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Desalination may be accomplished by
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Removing dissolved salts from the ocean water or from brackish water in aquifers or lakes
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Disadvantages of desalination
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High cost and it produces large quantities of briny wastewater that contains lots of salt and other minerals
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It is most economically and environmentally sound to focus water resource management on
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Prevention (don’t pollute)
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Irrigation efficiency can be improved by
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Drip irrigation
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List ways to improve water efficiency
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Use drip irrigation, recycle water from house, xeriscaping

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