Groundwater freshening following coastal progradation and land reclamation of the Po Plain, Italy [Rafraîchissement des eaux souterraines à la suite d’une progradation côtière et d’une réhabilitation des terrains de la plaine du Pô, Italie] [Addolcimento delle acque sotterranee a seguito di pro-gradazione e bonifica costiera nella Pianura Padana (Italia)] [Dulcificação (freshening) de águas subterrâneas seguindo o avanço costeiro e recuperação de terras da Planície do Pó, Itália] [Conversión del agua subterránea en agua dulce después de una progradación costera y recuperación de tierras en la llanura del Po, Italia]

Many coastal areas historically were inundated by seawater, but have since undergone land reclamation to enable settlements and farming. This study focuses on the coastal unconfined aquifer in the Po Plain near Ravenna, Italy. Freshwater is present as isolated thin (1–5 m) lenses on top of brackish to saline water. Historical maps show large areas of sea inundation until approximately 150–200 years ago when coastal progradation and construction of the drainage canals began. Since then, the aquifer has been freshening from recharge. A three-dimensional SEAWAT model is used to simulate a 200-year freshening history, starting with a model domain that is saturated with seawater, and applying recharge across the top model layer. Calibration to the observed concentrations for discrete depths within many monitoring wells is remarkably good. The current distribution of freshwater is largely controlled by the drainage network. Within and adjacent to the drains, the groundwater has high salinity due to up-coning of salt water. Between drains, the surface layers of the aquifer are fresh due to the flushing action of recharge. The modeling results are consistent with cation exchange processes revealed in the groundwater chemistry and with freshwater lenses identified in electrical resistivity soundings. © 2015 Springer-Verlag Berlin Heidelber