Search results
Results From The WOW.Com Content Network
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 ...
In confined aquifers , the cone of depression is a reduction in the pressure head surrounding the pumped well. When a well is pumped, the water level in the well is lowered. By lowering this water level, a gradient occurs between the water in the surrounding aquifer and the water in the well. Because water flows from high to low water levels or ...
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 ...
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 ...
The Dupuit–Forchheimer assumption holds that groundwater flows horizontally in an unconfined aquifer and that the groundwater discharge is proportional to the saturated aquifer thickness. It was formulated by Jules Dupuit and Philipp Forchheimer in the late 1800s to simplify groundwater flow equations for analytical solutions.
Groundwater discharge is the volumetric flow rate of groundwater through an aquifer. Total groundwater discharge, as reported through a specified area, is similarly expressed as: = where Q is the total groundwater discharge ([L 3 ·T −1]; m 3 /s), K is the hydraulic conductivity of the aquifer ([L·T −1]; m/s),
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.
(unconfined), where S y is the specific yield of the aquifer. Note that the partial differential equation in the unconfined case is non-linear, whereas it is linear in the confined case. For unconfined steady-state flow, this non-linearity may be removed by expressing the PDE in terms of the head squared: