Spacing of Drainage Wells in a Layered Aquifer

Abstract

A theory is presented to determine spacing of identical drainage wells that, by discharging groundwater simultaneously from a layered aquifer, will lower a water table to a preassigned level and maintain it. The theory has been developed by solving a mathematical boundary value problem. The wells are located on a certain regular grid, and the aquifer receives a uniform vertical recharge from rainfall or excess irrigation. The theory shows that the spacing depends on the thickness and hydraulic conductivity of each permeable layer tapped by the wells, the maximum allowable drawdown, the uniform vertical recharge, the radius of the wells, and the well grid geometry. A table of values of a function, useful for determining spacing of wells to be tapped in an aquifer that may consist of any number of permeable layers, is given.