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| 6204022511 | Availability of Freshwater | only about 0.024% of the earth's water supply is available to us as liquid fresh water | 0 | |
| 6204022512 | Groundwater | some precipitation infiltrates the ground and is stored in spaces in soil and rock; water in these spaces is one of most important sources of fresh water; moves from high to low elevation | 1 | |
| 6204022513 | Zone of Saturation | a certain depth where these spaces are completely filled with water | 2 | |
| 6204022514 | Water Table | the top of the zone of saturation | 3 | |
| 6204022515 | Aquifers | geological layers deeper down like caverns and porous, layers of sand, gravel, or bedrock through which groundwater flows; contain much more freshwater than lakes and rivers | 4 | |
| 6204022516 | Renewable Aquifers | replenished naturally by precipitation that percolates down through the soul and rock (natural recharge); some others are recharged by lateral recharge from nearby streams; refill slowly | 5 | |
| 6204022517 | Nonrenewable Aquifers | get very little, if any, recharge; deep underground from thousands of years ago; withdrawing will amount to mining a nonrenewable resource - a major problem in today's societies | 6 | |
| 6204022518 | Surface Water | the freshwater that flows across the earth's land surface and into rivers, streams, lakes, and reservoirs | 7 | |
| 6204022519 | Surface Runoff | precipitation that does not return to the atmosphere by evaporation or infiltrate into the ground | 8 | |
| 6204022520 | Watershed | drainage basin; the land fro which surface water drains into a river, lake, wetland, or other body of water | 9 | |
| 6204022525 | Global Outlook: Use of World's Freshwater | irrigation is the biggest use of eater (70%), then industries (20%), and cities and residences (10%) | 10 | |
| 6204022526 | Freshwater Resources in the United States | the US has plenty of freshwater but supplies vary depending on climate; in East water is used for energy, cooling, and manufacturing | 11 | |
| 6204022527 | Emerging Water Shortages | 41% of world's population lives in river basins that do not have enough freshwater; falling water tables, bodies of water running dry | 12 | |
| 6204022528 | Ownership and Management | disputes over government or private management; 85% of Americans get water from publicly owned utilities | 13 | |
| 6204022529 | Competition for World's Water and Resources | cities are outbidding farmers for water supplies from rivers and aquifers; countries are importing grain as a way to reduce water use; more crops are being used to produce biofuel | 14 | |
| 6204022530 | Water Options | get more water from rivers and aquifers, desalinate ocean water, waste much less water | 15 | |
| 6204022531 | Groundwater Depletion | aquifers are being depleted faster than they are being renewed; over pumping can increase gap between rich and poor, cause land to sink, and contaminate with saltwater | 16 | |
| 6204022532 | Withdrawing Groundwater Advantages | useful for drinking and irrigation, available year round and everywhere, renewable, no evaporation losses, cheaper to extract than most surface waters | 17 | |
| 6204022533 | Withdrawing Groundwater Disadvantages | depletion from over pumping, sinking of land from over pumping, pollution, saltwater intrusion, reduced water flows into surface waters, increased cost and contamination with more depth | 18 | |
| 6204022534 | Using Aquifers More Sustainably | requires controlling the rate of water removal, identifying and protecting water recharge zones from development, wasting less water, and slowing population growth | 19 | |
| 6204022535 | Groundwater Depletion Prevention | waste less water, subsidize water conservation, ban new wells and aquifers near surface water, retire groundwater withdrawal rights in critical areas, do not grow water intensive crops | 20 | |
| 6204022536 | Groundwater Depletion Control | raise price of water to discourage waste, tax water pumped from wells near surface water, set and enforce minimum stream flow levels | 21 | |
| 6204022537 | Advantages and Disadvantages to Large Dams | large dams and reservoirs produce cheap electricity, reduce downstream flooding, and provide year-round water for irrigating crop land but also displace people and disrupt aquatic systems; advantages include less flooding, electricity, water for irrigation and recreational activities; disadvantages include tensions among shared countries, and reducing downstream flow | 22 | |
| 6204022538 | Salton Sea | a shallow saline lake in S California, in the Imperial Valley, formed by the diversion of water from the Colorado River into a salt-covered depression; slowly drying up mainly due to evaporation | 23 | |
| 6204022539 | Lake Chad | a lake in Africa at the junction of four countries: Cameroon, Chad, Niger, and Nigeria. 5000 to 10,000 sq. mi.; similar situation to Salton Sea where it is slowly drying up | 24 | |
| 6204022540 | Aral Sea | a lake in Kazakhstan and Uzbekistan (formerly Soviet Union), east of the Caspian Sea, formerly the fourth largest lake in the world: shallow and saline, now badly polluted; use of its source waters for irrigation led to a loss of over 50% of its area between 1967 and 1997, after which the reduction began to be slowed. Area originally (to 1960) about 68 000 sq km (26 400 sq miles); water area reduced by 2004 to about 17 158 sq km (6625 sq miles) and the lake divided into sections; diverted water was mostly used for irrigation | 25 | |
| 6204022541 | Colorado River Basin | This river has so many dams and withdrawals that it does not reach the sea; 14 major dams and reservoirs; supplies water mainly to California but is also used for Nevada and other states around; 30 million people use for recreation; four major problems: includes driest land in US, only modest flow of water, more allocated water than it can supply, water withdrawn mainly for agriculture and urban use (80% for agriculture), evaporation, leakage, siltation (Lake Mead and Lake Powell) | 26 | |
| 6204022542 | China's Three Gorges Dam | debate over advantages and disadvantages; world's largest; helps reduce flooding and provide electricity but displaces many people and will cause flooding in different areas; may even collapse because it is built over a major seismic fault | 27 | |
| 6204022543 | Dam Removal | some dams are being removed for ecological reasons and because they have outlived their usefulness; cost for taxpayers is high, can expose downstream to toxic sediments | 28 | |
| 6204022544 | Advantages and Disadvantages to Water Transfer | advantages: makes water-poor areas more suitable for growing food, grazing, and other business activities; makes it more likely that businesses will invest, jobs will be created, and economies will be strengthened in those areas; disadvantages: encourages unsustainable water use | 29 | |
| 6204022545 | California Experience | California's Water Project uses mazes, dams, pumps, and aqueducts to transport water between areas; subsidized water contracts | 30 | |
| 6204022546 | Desalination | removing dissolved salts from ocean water or from brackish water in aquifers or lakes for domestic use; Israel uses prominently; two major problems: very costly and takes a lot of energy | 31 | |
| 6204022547 | Distillation | heating saltwater until it evaporates, leaves behind salts in solid form, and condenses as freshwarer | 32 | |
| 6204022548 | Reverse Osmosis | microfiltration; uses high pressure to force salt water through a membrane filter with pores small enough to remove the salt (pushes freshwater out of salt water) | 33 | |
| 6204022549 | Cloud Seeding and Towing Icebergs or Gigantic Water Bags | seeding clouds with tiny particles of chemicals to increase rainfall or towing icebergs or huge bags filled with freshwater to dry coastal areas is unlikely to provide significant amounts of freshwater; problems: few clouds to seed, no compelling evidence that it works, large amounts of chemicals into soil and water systems, legal disputes over cloud water | 34 | |
| 6204022550 | Benefits of Reducing Water Waste | we waste 2/3 of the water we use through evaporation, leaks, and other losses; we can cut it to 15%; we charge too little for water; water is heavily subsidized; establishing lifeline rates (minimum) would be effective; lack of government subsidies for improving efficiencies of water use | 35 | |
| 6204022551 | Wasting Less Water for Irrigation and Crop Yields | 60% of world's irrigation water is wasted; improved techniques can decrease it to 5-20%; flood irrigation is terrible; better methods are center pivot, low pressure sprinkler, drip irrigation, microirrigation systems (perforated tubes at or below ground level), gravity flow are less effective, can also use soil moisture detectors | 36 | |
| 6204022552 | 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, grow water efficient crops, irrigate with treated urban waste water, import water intensive crops and meats, rainwater harvesting | 37 | |
| 6204022553 | 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 appliances, collect and reuse household water for irrigations and non edible plants, purify and reuse water for domestic use, don't waste energy | 38 | |
| 6204022554 | Reducing Flood Damage | preserve forests on watersheds, preserve and restore wetlands in floodplains, tax all developments on floodplains, use floodplains primarily for recharging aquifers, sustainable agriculture and forestry, and recreation; strengthen and deepen streams, build levees or floodwalls along streams, build dams | 39 | |
| 6204022555 | What Can We Do? | use water saving appliances, shower instead of taking baths, stop water leaks, turn off sink faucets when not directly using, flush toilets only when necessary, wash only full loads of laundry, used recycled water for lawns and gardens and car washing, wash a car from bucket and use hose for rinsing, use water efficient plants, water gardens in evenings or early mornings, sweep or blow off driveway instead of hosing them down, use drip irrigation and mulch for gardens and flowerbeds | 40 | |
| 6204022556 | Hydrologic Cycle | the hydrologic cycle begins with the evaporation of water from the surface of the ocean; as moist air is lifted, it cools and water vapor condenses to form clouds; moisture is transported around the globe until it returns to the surface as precipitation. | 41 | |
| 6204022557 | Transpiration | the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere; transpiration is essentially evaporation of water from plant leaves | 42 | |
| 6204022558 | Natural Recharge | the replenishment of groundwater storage from naturally-occurring surface water supplies such as precipitation and stream flows | 43 | |
| 6204022559 | Drainage Basin | drainage basin or catchment basin is an extent or an area of land where all surface water from rain, melting snow, or ice converges to a single point at a lower elevation, usually the exit of the basin, where the waters join another body of water, such as a river, lake, reservoir, estuary, wetland, sea, or ocean | 44 | |
| 6204022560 | Aqueduct | an artificial channel for conveying water, typically in the form of a bridge supported by tall columns across a valley | 45 | |
| 6204022561 | Irrigation Types | flood irrigation-delivers far more water than necessary; center pivot-pumped from underground and sprayed from mobile boom with sprinklers; low pressure sprinkler-uses pumps to spray on crops; low energy precision application sprinklers-center pivot method, sprays water closer to ground and with larger droplets; drip irrigation-microirrigation, perforated plastic tubing is at or below ground level deliver water to plant roots; gravity flow-water comes from nearby aqueduct or river | 46 | |
| 6204022562 | Ogallala | shallow water table aquifer surrounded by sand, silt, clay and gravel located beneath the Great Plains in the United States; most important in the US | 47 | |
| 6204022563 | Riparian Rights | a system for allocating surface water among those who possess land along its path. It has its origins in English common law. Riparian water rights exist in many jurisdictions with a common law heritage, such as Canada, Australia, and states in the eastern United States. | 48 | |
| 6204022564 | Floodplain | an area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding | 49 | |
| 6204022565 | Living on Floodplains in Bangladesh | increased flooding from upstream deforestation of Himalayan mountain slopes and clearing of mangrove forests on its coastal floodplains; increased runoff from the soil and monsoon rains increase severity of flooding; living on the floodplain means coping with storm surges, cyclones, tsunamis, earthquakes, etc | 50 |
