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The Ogallala Aquifer (oh-gə-LAH-lə) is a shallow water table aquifer surrounded by sand, silt, clay, and gravel located beneath the Great Plains in the United States. As one of the world's largest aquifers, it underlies an area of approximately 174,000 sq mi (450,000 km 2) in portions of eight states (South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, and Texas). [1]
Cross section showing the water table varying with surface topography as well as a perched water table Cross-section of a hillslope depicting the vadose zone, capillary fringe, water table, and the phreatic or saturated zone. (Source: United States Geological Survey.) The water table is the upper surface of the zone of saturation.
This is a list of rivers in the continental United States by average discharge (streamflow) in cubic feet per second. All rivers with average discharge more than 15,000 cubic feet per second are listed.
USGS operates a number of water-related programs, notably the National Streamflow Information Program [22] and National Water-Quality Assessment Program. [23] USGS Water data is publicly available from their National Water Information System [24] database.
Aquifers of the United States are organized by national principal aquifer codes and names assigned by the National Water Information System (NWIS). Aquifers are identified by a geohydrologic unit code (a three-digit number related to the age of the formation) followed by a 4 or 5 character abbreviation for the geologic unit or aquifer name.
McFeeters index: If looking for water bodies or change in water level (e.g. flooding), then it is advisable to use the green and NIR spectral bands [18] or green and SWIR spectral bands. Modification of normalised difference water index (MNDWI) has been suggested for improved detection of open water by replacing NIR spectral band with SWIR. [19]
Static level is the level of water in the well when no water is being removed from the well by pumping. [8] Water table is the upper level of the zone of saturation, an underground surface in which the soil or rock is permanently saturated with water. [9] Well yield is the volume of water per unit time that is produced by the well from pumping. [8]
Within the USGS, the Water Resources Division carries the responsibility for monitoring water resources. To establish a stream gauge, USGS personnel first choose a site on a stream where the geometry is relatively stable and there is a suitable location to make discrete direct measurements of streamflow using specialized equipment.