ENVS 1000U Lecture Notes - Lecture 16: Aquifer, Water Cycle, Evapotranspiration
14 Mar 2016
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Document Summary
Water seems abundant but drinkable water is in short supply. Freshwater = relatively pure, with few dissolved salts: only 3% of earth"s water is fresh, most freshwater in glaciers/ice caps. Wetlands are valuable: provide ecological services: Filter pollutants: people have drained wetlands, mostly for agriculture. Groundwater plays a key role in water availability. Different regions have different amounts of groundwater, surface water and precipitation. Many areas with high population density are water-poor often face shortages. Monsoon seasons bring concentrated storms: half a region"s annual rain may fall in a few hours. Climate change will affect hydrological cycle: altered precipitation patterns, early seasonal (spring) runoff. Lecture 16: more evapotranspiration, intensified droughts, melting glaciers, flooding. Increasing probability of even less water for more people. Impressive engineering projects have harnessed freshwaters: 60 % of world"s largest 227 rivers have been impacted, many major rivers cross national borders. Consumption of water in most of world unsustainable: depleting many sources of surface water/groundwater.
