Calculating equivalent radial distances for determination of transmissivity and storativity using drawdown data from a multiple pumping well systems

Abstract

Abstract A method is presented for the determination of aquifer transmissivity (T) and storativity (S), using distance-drawdown data from a wellfield with multiple pumping and observation wells. An equivalent radial distance calculated for each observation well, the aggregate system pumping rate (Q), and drawdown data for two or more nearby observation wells are used in the calculation of T and S. The method described can be used to evaluate complex pumping systems, as it can accommodate multiple pumping wells discharging at the same or at different rates, and varying well spacings. It can also accommodate a combination of both pumping and recharge wells concurrently operating. This versatile approach is particularly useful in determining the aquifer transmissivity and storativity for a series of extraction wells installed to remediate ground water, for use in subsequent capture zone and other design/performance evaluations. It is also useful for determining aquifer characteristics for evaluation of an operating water supply wellfield.