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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 surface ...
Drawdown (economics) The drawdown is the measure of the decline from a historical peak in some variable (typically the cumulative profit or total open equity of a financial trading strategy). [1] Somewhat more formally, if is a stochastic process with , the drawdown at time , denoted , is defined as: The average drawdown (AvDD) up to time is ...
In hydrogeology, an aquifer test (or a pumping test) is conducted to evaluate an aquifer by "stimulating" the aquifer through constant pumping, and observing the aquifer's "response" ( drawdown) in observation wells. Aquifer testing is a common tool that hydrogeologists use to characterize a system of aquifers, aquitards and flow system boundaries.
Well test. In hydrology, a well test is conducted to evaluate the amount of water that can be pumped from a particular water well. More specifically, a well test will allow prediction of the maximum rate at which water can be pumped from a well, and the distance that the water level in the well will fall for a given pumping rate and duration of ...
The specific storage is the amount of water that a portion of an aquifer releases from storage, per unit mass or volume of the aquifer, per unit change in hydraulic head, while remaining fully saturated. Mass specific storage is the mass of water that an aquifer releases from storage, per mass of aquifer, per unit decline in hydraulic head: where.
In confined aquifers ( artesian ), 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 ...
Risk–return ratio. The risk-return ratio is a measure of return in terms of risk for a specific time period. The percentage return (R) for the time period is measured in a straightforward way: where and simply refer to the price by the start and end of the time period. The risk is measured as the percentage maximum drawdown (MDD) for the ...
The Calmar ratio uses a slightly modified Sterling ratio – average annual rate of return for the last 36 months divided by the maximum drawdown for the last 36 months – and calculates it on a monthly basis, instead of the Sterling ratio's yearly basis. [1] Young believed the Calmar ratio was superior because. The Calmar ratio changes ...