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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 unconfined, meaning it does not have a confining layer (an aquitard or aquiclude) between it and the ...
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 ...
There are two types of aquifers: confined and unconfined. In confined aquifers, there is an overbearing layer called an aquitard, which contains impermeable materials through which groundwater cannot be extracted. In unconfined aquifers, there is no aquitard, and groundwater can be freely extracted from the surface.
It is recommended to name the SVG file “Groundwater (aquifer, aquitard, 3 type wells).svg”—then the template Vector version available (or Vva) does not need the new image name parameter. Licensing
This is an accepted version of this page This is the latest accepted revision, reviewed on 1 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 ...
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 ...
In an unconfined aquifer, the saturated thickness is defined as the vertical distance between the water table surface and the aquifer base. If ∂ h / ∂ z = 0 {\displaystyle \partial h/\partial z=0} , and the aquifer base is at the zero datum, then the unconfined saturated thickness is equal to the head, i.e., b=h .
For a confined aquifer or aquitard, storativity is the vertically integrated specific storage value. Specific storage is the volume of water released from one unit volume of the aquifer under one unit decline in head. This is related to both the compressibility of the aquifer and the compressibility of the water itself.