Prediction of salinization effects in a shallow coastal aquifer due to sands quarry excavation: monitoring and modelling variable density flow (Ferrara, Italy)

In reclamated lands of Ferrara coastal plain (Emilia-Romagna region, Northern Italy) the fresh/salt water interface inside shallow aquifers is the result of a delicate equilibrium between the fresh water recharge from the top and the presence of salt water in the deepest sediments. Sands quarries below groundwater table in these shallow aquifers can affect groundwater flow and the interface position. In the studied site salinity, temperatures and groundwater levels have been monitored continuously over 1 year and allowed the definition of the aquifer conceptual model. Then a variable density groundwater model has been set up with VisualMODFLOW 4.1 and different simulation with SEAWAT-2000 have been performed, in order to predict the effects of the sand quarry on the interface position. First results show that 5 years after the quarry excavation the groundwater level in the aquifer decreases and the interface rises of about 2 m in the excavation area.