GEOL 100 Lecture Notes - Lecture 28: Phreatic Zone, Water Table, Hydraulic Head
29 Apr 2019
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Document Summary
95. 96% of water on earth is salt water in oceans and seas. Glaciers and polar ice is not really useful to us--2. 97% Used to cool machine parts so they keep working. Need 20 inches of precipitation for agriculture to be possible without. Most of the midwest does not get that amount of precipitation. Water table position changes depth with rainfall. The water table is generally below the surface so that water can seep in. Natural springs: water can flow out where the water table intersects with the surface. Porosity: the percent of open space within a rock. Permeability/ hydraulic conductivity: the connectedness of the pore spaces. In the saturated zone, flow is more complicated. Flow in the unsaturated zone is straight downward. Well creates an artificial spot of low pressure, so that water is drawn to well heads. Confined aquifer is situated between two aquicludes (beds of low permeability) Flow of artesian well is governed by difference in pressure.
