Modellazione numerica del flusso nell'acquifero freatico dell'Alta Pianura Veneta per la definizione del bilancio idrogeologica

A 3D groundwater flow model was developed, with MODFLOW-2005 code (Harbaugh, 2005), to assess and validate the current water balance for the uncon-fined aquifer in the High Venetian Plain, through inverse modeling performed by using an automatic optimization software (PEST; Doherty, 2015). The automatic calibration approach was developed implementing three different scenarios for the hydraulic conductivity distribution and was aimed to minimize the residual between observed and simulated hydraulic head in the least squared sense by adjusting the values of the calibration parameters. The highly parameterized inversion turned out to be the best way to minimize the objective function, providing a model consistent with the current water balance for the aquifer estimated by previous studies (Cambruzzi et al., 2010; Fabbri et al., 2016), except for the Brenta and Piave rivers dispersion and the outflow from the southern margin of the model domain. Starting from the calibrated model and the results obtained from a climate model developed for the area (Baruffi et al., 2012), three predictive simulations were also performed for the period 2070-2100, considering different irrigation policies. The results of the predictive simulations suggest that the surface irrigation system could be a valuable way to avoid further withdrawal of the water table, which the aquifer has been experiencing through the last decades