Search results
Results from the WOW.Com Content Network
An unconfined aquifer has no impermeable barrier immediately above it, such that the water level can rise in response to recharge. A confined aquifer has an overlying impermeable barrier that prevents the water level in the aquifer from rising any higher. An aquifer in the same geologic unit may be confined in one area and unconfined in another.
is the volume of water drained, and is the total rock or material volume. It is primarily used for unconfined aquifers, since the elastic storage component, , is relatively small and usually has an insignificant contribution. Specific yield can be close to effective porosity, but there are several subtle things which make this value more ...
[1] [2] In an unconfined aquifer (water table), this is an actual depression of the water levels. 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.
(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:
This holds in particular for water, which is by far the most studied confined liquid. Liquids under sub-millimeter confinement (e.g. in the gap between rigid walls) exhibit a nearly solid-like mechanical response and possess a surprisingly large low-frequency elastic shear modulus, which scales with the inverse cubic power of the confinement ...
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.
This surface usually coincides with the water table. The slope of the phreatic surface is assumed to indicate the direction of groundwater movement in an unconfined aquifer. The phreatic zone, below the phreatic surface where rock and soil are saturated with water, is the counterpart of the vadose zone, or unsaturated zone
Confined water may refer to: Confined liquid, a liquid subject to geometric constraints on a nanoscopic scale; Confined water (diving), a diving environment that is enclosed and bounded sufficiently for safe training purposes; Confined waters (navigation), an area of the sea where the width of the safely navigable waterway is small relative to ...