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In subsurface hydrogeology, drawdown is the reduction in hydraulic head observed at a well in an aquifer, typically due to pumping a well as part of an aquifer test or well test. In surface water hydrology and civil engineering , drawdown refers to the lowering of the surface elevation of a body of water, the water table, the piezometric ...
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 ...
Often the well efficiency is determined from this sort of test, this is a percentage indicating the fraction of total observed drawdown in a pumping well which is due to aquifer losses (as opposed to being due to flow through the well screen and inside the borehole). A perfectly efficient well, with perfect well screen and where the water flows ...
where s is the drawdown (change in hydraulic head at a point since the beginning of the test in units of distance), u is a dimensionless parameter, Q is the discharge (pumping) rate of the well (volume per unit time), T and S are the transmissivity and storativity of the aquifer around the well (distance squared per unit time and dimensionless ...
Pumps being used to dewater a spillway at Baldhill Dam. Dewatering / d iː ˈ w ɔː t ər ɪ ŋ / is the removal of water from a location. This may be done by wet classification, centrifugation, filtration, or similar solid-liquid separation processes, such as removal of residual liquid from a filter cake by a filter press as part of various industrial processes.
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Japanese automaker Nissan finds itself at a crossroads.Nissan was poised to participate in a megamerger with rival Honda (), and it was a huge development when the talks were revealed late last year.
Drawdown (economics), decline in the value of an investment, below its all-time high; Drawdown (hydrology), a lowering of a reservoir or a change in hydraulic head in an aquifer, typically due to pumping a well; Drawdown card, used for testing paints and coatings through wet film preparation; Drawdown chart, paper used to test various coating ...