Multi-scenario numerical modeling applied to groundwater contamination: the Popoli Gorges complex aquifer case study (Central Italy)

In this research, a multi-scenario numerical modeling was implemented to assess the effects of changes to abstraction patterns in the Sant'Angelo well-field (central Italy) and their implications on the aquifer hydrodynamic and the advective transport of contaminants. Once implemented and calibrated the steady-state numerical model by means of MODFLOW-2005, the well-field turning off scenario was modelled. In addition, the numerical results were analyzed by means of the post-processors ZONEBUDGET and MODPATH, to assess respectively the contribution of each hydrogeological feature to the total budget and the advective transport of contaminant particles. Comparing the two steady-state numerical models and the relative particle tracking analyses, the well-field turning off, although no longer acting as a hydraulic barrier, increased the residence time of contaminant particles and limited their mobility in the aquifer. Furthermore, the general decrease in groundwater abstractions also caused a higher increase in river flow, favoring contaminants' dilution in surface water.