Tuesday, November 20, 2007

A short note on Groundwater

Groundwater is the water flowing within aquifers under the water table. Within aquifers, the water runs through the pore spaces in unconsolidated sediments and the fractures of rocks. Groundwater is revitalized from, and finally runs to, the surface naturally; natural discharge often occurs at springs and seeps and can form oases or swamps. The Groundwater is as well sometime withdrawn for agricultural, municipal and industrial use through artificial or the man-made wells. The study of the groundwater distribution and the movement is hydrogeology.

Groundwater can be a long-term 'reservoir' of the natural water cycle as different to short-term water reservoirs like the atmosphere and the fresh surface water (which have habitation times from minutes to years). This deep groundwater (which is somewhat distant from the surface recharge) can take extremely long time to complete its natural cycle. Groundwater is of course replenished by surface water from precipitation, the streams, and the rivers when this recharge reaches the water table. It is expected that the volume of groundwater is fifty times that of surface freshwater; the icecaps and the glaciers are the only bigger reservoir of fresh water on earth.


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