groundwater |
english |
Difino
| • | Groundwater is water which may be flowing within aquifers below the water table. Within aquifers, the water flows through the pore spaces in unconsolidated sediments and the fractures of rocks. Groundwater is recharged from, and eventually flows to, the surface naturally; natural discharge often occurs at springs and seeps and can form oases or swamps. Groundwater is also often withdrawn for agricultural, municipal and industrial use through man-made wells. The study of the distribution and movement of groundwater is hydrogeology. Groundwater can be a long-term 'reservoir' of the natural water cycle (with residence times from days to millennia), as opposed to short-term water reservoirs like the atmosphere and fresh surface water (which have residence times from minutes to years). The figure shows how deep groundwater (which is quite distant from the surface recharge) can take a very long time to complete its natural cycle. Groundwater is naturally replenished by surface water from precipitation, streams, and rivers when this recharge reaches the water table. It is estimated that the volume of groundwater is fifty times that of surface freshwater; the icecaps and glaciers are the only larger reservoir of fresh water on earth. Usable groundwater is contained in aquifers, which are subterranean areas (or layers) of permeable material (like sand and gravel) that channel the groundwater's flow. Aquifers can be confined or unconfined. If a confined aquifer follows a downward grade from a recharge zone, groundwater can become pressurized as it flows. This can create artesian wells that flow freely without the need of a pump. The top of the upper unconfined aquifer is called the water table or phreatic surface, where water pressure is equal to atmospheric pressure. Typically groundwater is thought of as liquid water flowing through shallow aquifers, but technically it can Source: [wikipedia: groundwater] |
water_resources:environment
| Fayette County Groundwater Conservation District | ||
| mission is to protect and conserve the underground water resources for the current and future residents of fayette county, texas. offers publications, information on projects and services as well as general information. | ||
| George F. Pinder | ||
| professor of civil and environmental engineering, university of vermont. information about past and present research in groundwater modeling, including mathematical evaluation of contamination problems. | ||
| Ground-Water Remediation Technologies Analysis Center | ||
| information on innovative groundwater remediation technologies. gwrtac prepares reports by technical teams selectively chosen from concurrent technologies corporation (ctc), the university of pittsburgh, and other supporting institutions. | ||
| PEST Parameter Estimation Groundwater Modeling Workshop | ||
| the groundwater resources association is conducting a workshop "model calibration and predictive uncertainty analysis using pest" april 19-21, 2004, santa ana, ca | ||
| The Groundwater Foundation | ||
| dedicated to the education about and preservation of our most important natural resource. | ||
| UK Groundwater Forum | ||
| source of information and a platform for information exchange on groundwater topics in and for the uk. | ||
| Water Framework Directive - Groundwater Statistics | ||
| report from a european union project to develop statistical methods for data aggregation for assessment of groundwater quality status, including trend assessment. | ||
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