Step drawdown tests and slug tests: permeability distribution in an area of the middle Venetian plain (Veneto Region, Northeast Italy)

This article presents the results of a hydrogeological investigation conducted near Scorzé (Treviso, Italy), where several step drawdown tests and slug tests were conducted to characterize a confined aquifer. The studied area, which covers 94000 m2 in the provinces of Venice, Treviso and Padua, is located in the middle Venetian plain (Fig. 1). The study area is characterized by the presence of a multi-layered aquifer system composed of ten confined aquifers ranging from 15 to 310 m in depth (Cambruzzi et al., 2010). In this system, permeable fluvio-glacial deposits are interbedded with marine layers of lower conductivity. The investigations focused on the first confined aquifer, which is currently the most exploited by both public and private water companies. This aquifer is an alluvial gravel aquifer, with a thickness of approximately 30 m and a depth ranging from 15 to 60 m b.g.l. This aquifer is recharged from rainfall, irrigation and groundwater-river interactions at the large unconfined aquifer located in the high Venetian plain toward the N-NE. The groundwater flows from the recharge area to the sea, and the hydraulic head ranges from 24.8 to 7.3 m a.s.l. Moving away from the recharge area, the first aquifer becomes progressively artesian, with the hydraulic head above ground during the year or periodically in the rainy season. This condition has favored extensive groundwater exploitation in the recent past, with more than one hundred wells for private supply drilled in the study area.