Sequential aquifer tests at a well field, Montalto Uffugo Scalo, Italy

This paper investigates our ability to characterize an aquifer using a sequential aquifer test in a well field that consists of six wells. During the test, we pumped water out from the aquifer at one well and monitored the water level changes at the rest of the wells to obtain a set of five well hydrographs. By pumping at another of the six wells, we obtained another set of five hydrographs. This procedure was repeated until each of the six wells was pumped. We then analyzed the six sets of hydrographs using the classical drawdown-time, the drawdown-distance, and the drawdown-distance/time methods. Results of the analysis confirm recent findings that the transmissivity estimates vary significantly at early time and stabilize at late time. At late time, the estimated values from all hydrographs are similar overall but vary slightly according to the locations of the pumping and observation wells. In contrast, storage coefficient estimates stabilized rapidly to distinct values associated with the well locations. We subsequently used a hydraulic tomography approach to include all hydrographs from the sequential aquifer test to estimate the spatially varying transmissivity and storage coefficient fields. The estimated fields appear to be realistic: They reflect the geologic setting and the behaviors of the well hydrographs, although more definitive confirmation is needed.