Model calibration using the automatic parameter estimation procedure (PEST) of the North-eastern zone of the Milan Functional Urban Area (Italy)

Abstract

The FUA of Milan is a densely populated area (2.254.263 inhabitants) where the water supply is guaranteed exclusively by underground water withdrawals. For this reason, the protection of groundwater quality is one of the priorities of the Lombardy Region's environmental policies. Recently, a program of studies and interventions has been started with the aim of identifying the main plumes of contamination from chlorinated solvents, distinguishing their impact from that linked to diffused pollution. This article presents the flow model developed for the NE sector of FUA in Milan, with code MODFLOW2005 (Harbaugh, 2005) and automatically calibrated using PEST (Doherty, 2014, 1994). The modelling domain comprises the northern sector of the municipality of Milan (extension equal to 119 km2). The area has been used as a pilot area to develop and test a new methodology that combines statistics and modelling in order to distinguish the contribution of the sources of contamination on time compared to the diffused ones.