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An aquifer in the same geologic unit may be confined in one area and unconfined in another. Unconfined aquifers are sometimes also called water table or phreatic aquifers, because their upper boundary is the water table or phreatic surface (see Biscayne Aquifer). Typically (but not always) the shallowest aquifer at a given location is ...
Animals living within the phreatic zone of groundwater aquifers can be referred to as phreatobites. [4] They are usually isopod or amphipod crustaceans such as species of Stygobromus , though there is also a genus of snails ( Phreatodrobia ) and Phreatobius are a genus of catfish living within flooded leaf litter.
Shallow or unconfined wells are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer). [citation needed] Deep or confined wells are sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of deep aquifers are classified ...
Aquifers can be unconfined, where the top of the aquifer is defined by the water table, or confined, where the aquifer exists underneath a confining bed. [5] There are three aspects that control the nature of aquifers: stratigraphy, lithology, and geological formations and deposits. The stratigraphy relates the age and geometry of the many ...
The following is a partial list of aquifers around the world. A category-based list of aquifers is also available. Africa. Bas Saharan Basin;
Surficial aquifers are shallow aquifers typically less than 50 feet (15 m) thick, but larger surficial aquifers of about 60 feet (18 m) have been mapped. They mostly consist of unconsolidated sand enclosed by layers of limestone, sandstone or clay and the water is commonly extracted for urban use.
Aquifer types include: confined (sealed and possibly containing “fossil” water); unconfined (capable of receiving inflow); and Artesian (an aquifer in which the hydraulic pressure will cause the water to rise above the upper confining layer). arable land - land that can be used for growing crops.
The pumping rate in the well will affect the size of the cone. Also, the type of aquifer material, such as whether the aquifer is sand, silt, fractured rocks, karst, etc., also will affect how far the cone extends. The amount of water in storage and the thickness of the aquifer also will determine the size and shape of the cone of depression.