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Electrical analogue for discharge versus time analysis in a pumping well

Summa, Gianpietro, Tataranni, Assunta, D’Abramo, Germano
Hydrogeology journal 2019 v.27 no.4 pp. 1527-1536
aquifers, capacitance, data collection, drawdown, hydraulic resistance, models
Novel findings about the general properties of an aquifer were obtained by applying the pumping approach introduced by Summa (2010). The approach of keeping the pump’s rotation speed constant was chosen over the well-known and widely used constant discharge method. The present analysis was performed on a set of unpublished data acquired during the same field test that was described in Summa (2010). The values of the instantaneous discharge and instantaneous drawdown were obtained. The contribution of the water already stored in the well to the overall capacitance of the aquifer was cancelled out for the field data that were processed. It was then possible to obtain a discharge-time function depending only upon the aquifer discharge. The discharge-time curve that was obtained showed a behaviour practically indistinguishable from the discharge-time curve for a resistor-inductor-capacitor (RLC) circuit with a direct current. By fully exploiting that circuit analogy, it was possible to evaluate the resistance, capacitance and inductance (inertia) of the aquifer. These parameters were estimated from the RLC solution that best fit the discharge-time curve. The value of the hydraulic resistance that was obtained was of the same order of magnitude as the inverse value of the transmissivity, already calculated for the same aquifer in previous work. This matching suggests that this model, as a future development of the present study, can be tested against the standard models regarding the determination of the traditional hydrogeological parameters. Summa G (2010) A new approach to the step-drawdown test, Water SA, 36(3):279–286.