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The breadth and depth of the aquifer generally decrease from north to south. Regions where the water level has declined in the period 1950–2015 are shown in yellow and red; regions where it has increased are shown in shades of blue. Data from the USGS Groundwater withdrawal rates (fresh water, all sources) by county in 2000. Source: National ...
Aquifers of the United States Withdrawal rates from the Ogallala Aquifer.. This is a list of some aquifers in the United States.. Map of major US aquifers by rock type. An aquifer is a geologic formation, a group of formations, or a part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to groundwater wells and springs.
This is an accepted version of this page This is the latest accepted revision, reviewed on 11 February 2025. Water located beneath the ground surface An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the water table (4), and three different wells (7, 8 and 9) dug to reach it. Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in ...
[13]: 418 Rainfall and snowmelt enter the groundwater where the aquifer is near the surface. Groundwater flow directions can be determined from potentiometric surface maps of water levels in wells and springs. Aquifer tests and well tests can be used with Darcy's law flow equations to determine the ability of a porous aquifer to convey water.
The USGS also utilizes data from The National Map Corps, which consists of volunteers who devote some of their time to provide cartographic information on structures. [ 4 ] The National Map is the official replacement for the USGS topographic map program .
The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, [1] which may be fresh, saline, or brackish, depending on the locality. It can also be simply explained as the depth below which the ground is saturated. The portion above the water table is the vadose zone. It may be visualized as the "surface ...
In 2020, another study led by the U.S. Geological Survey laid the groundwork for this issue alongCalifornia's 1,200-mile coast, andstate toxic substances control officials have sincestarted their ...
In 2015, the USGS unveiled the topoView website, a new way to view their entire digitized collection of over 178,000 maps from 1884 to 2006. The site is an interactive map of the United States that allows users to search or move around the map to find the USGS collection of maps for a specific area.