Groundwater yield, climatic changes and recharge variability:considerations arising from tbe modelling of a spring in tbe Umbria-Marcbe Apennines

This work is a first attempt at defining the effects of climatic variations on groundwater In central Italy, taking the Bagnara mountain spring located in the Umbria Marche Apennines as a sample system. In order to quantify the possible effects of climatic variations on this system, this spring system was modelled and calibrated in different stages by using the well-known Darcian MODFLOWcode of the USCS. The results obtained showed that the percentage decrease in yield related to a decrease in recharge would be higher than the percentage decrease in recharge, due to the fact that a decrease in recharge implies a change in the recharge area. These indications cause great concern, since the analysed spring, fed by an aquifer connected to a deep regional flow, is similar to many others in the Umbria Marche Apennines. Springs of this type represent one of the main sources of drinking water in the area, and depletion in their yield would lead to difficult/t management problems.