Environmental Geosciences Exam 4 Study Guide 97 of water salty and not consumable Chapter 10 Water The Importance of Water Properties of water H20 Polar has a negative charge one end of molecule has a positive electrical charge and the other end o Negative oxygen attracted to positive hydrogen o Forms hydrogen bond basis for many of water s physical properties High melting freezing point high boiling point Absorbs much heat w o substantially increasing High heat capacity temperature o Allows ocean to have a moderating influence on climate coastal Solvent areas it can dissolve many materials o Never completely pure in nature o Contains dissolved gases and mineral salts o Many substances dissolves cause water pollution Hydrologic Cycle and Our Supply of Fresh Water Hydrologic cycle water continuously circulates through the environment form the ocean to the atmosphere to the land and back to the ocean o Balance of the water resources in the ocean on land and in atmosphere o Provides continual renewable of the supply of freshwater on land Essential to terrestrial organism precipitation that remains on the surface of the land and does Surface water not seep down through the soil o Found in streams rivers lakes ponds reservoirs and wetlands o Wetlands areas of land covered with water for at least part of the year o Runoff of precipitation from land replenishes surface waters and is o Drainage basin watershed considered a renewable but finite resources or streams Underground formations collect and store water the area of land drained by a single river o Water originates as rain or melting snow seeps into soil o Travels until impenetrable layer stops o Groundwater the supply of freshwater under Earth s surface that is stored in underground aquifers Groundwater recharge downward movement accumulation Eventually goes to rivers wetlands springs or ocean o Aquifers underground reservoirs in which groundwater is stored Water Resource Problems 3 categories o 1 Too much water occurs when river s discharge can t be contained flooding within normal channel humans remove water absorbing plant cover from soil and construct buildings floodplain potential to flood the area bordering a river channel that has the fragile ecosystems in which plant growth is limited o 2 Too little water arid lands by lack of precipitation semiarid lands subject to frequent and prolonged droughts farmers increase productivity of these with irrigation receive more precipitation than deserts but are increasing importance for enough food population growth Aquifer depletion can be recharged by precipitation or melting snow the removal of groundwater faster than it Lowers water table the upper surface of the saturated zone of groundwater Subsidence aquifer depletion sinking of the land above it caused by o 3 Poor quality water Saltwater intrusion freshwater aquifer near the coast the movement of seawater into a Overdrawing of Surface Waters Estuaries become saltier when surface waters are overdrawn o Serve as breeding grounds for many species of birds and other animals West and Southwest particularly bad with overdrawing Colorado River basin o One of most serious water supply problems o Headwaters formed from snowmelt in Colorado Utah and Wyoming o Provides water for 30 million people o 1922 Colorado River Compact stipulates an annual allotment of 7 5 million acre feet of water to the lower Colorado California Nevada Arizona NM and remainder to upper Colorado Colorado Utah Wyoming overestimated average annual flow of river locked that estimate into multistate agreement population growth in upper Colorado lower becoming salty Salinization of Irrigated Soil salinization improper irrigation methods the gradual accumulation of salt in soil often as a result of o irrigation water contains small amounts of dissolved salts carried away through precipitation runoff in rivers irrigation water soaks into soil and does not run off into rivers continual application gradual accumulation of salt in soil rise to high level plants poisoned or roots dehydrated Global Water Issues Water supplies limited India China Mexico More population deplete freshwater supplies less water for crops of world s 200 major watersheds shared between at least 2 nations o International cooperation required to manage rivers o Heavily populated drainage basin for Rhine River in Europe 5 o Famines countries International Commission for Protection of the Rhine Main sources of pollution eliminated Water Management Main goal provide a sustainable supply of high quality water the wise use of water resources without harming the Sustainable water use essential functioning of the hydrologic cycle or the ecosystems on which present and future humans depend Supplies obtained by dams diverting water removing salt from seawater or salty groundwater desalinization Conservation reusing water recycling water improving water use efficiency Economic policies inexpensive waste raise price to reflect actual cost Dams and Reservoirs managing the Columbia River Dams generate electricity and ensure a year round supply of water in areas with seasonal precipitation or snowmelt o Populations that have outgrown other water sources o Heavy sediment deposition can occur in the reservoir behind a dam o Water that passes over does not have normal sediment load o River floor downstream of dam scoured deep cut channel that is a poor habitat for aquatic organisms o Many have fish ladders allow some of adult salmon to bypass the dams and continue upstream migration Water Conservation Reducing Agricultural Water Waste o Traditional irrigation flooding land or diverting water to fields through open channels o Plants absorb 40 of water that flood irrigation supplies rest o Microirrigation usually evaporates seeps into ground leaves fields as runoff conserves water by piping it to crops through sealed systems Drip trickle irrigation a type of irrigation that Pipes with tiny holes convey water directly to individual plants Substantially reduces water needed o Other measures lasers to level fields employing computer controlled technology to place hoses and time water release Reducing Water Waste in Industry costly o 5 major industries consume almost 90 of industrial water chemical products paper and pulp petroleum and coal primary metals food processing o stricter pollution control laws incentive for industries to conserve recapture purify and reuse water o International companies locate plants Reducing