Analysis of the climate change effects on the Bracciano lake (Italy) using numerical model application

Bracciano volcanic caldera lake (Italy) is part of the Sabatini Hydrogeological Unit. Studies indicate that the lake is in direct contact with the main aquifer. The area is exposed to continuous stresses from several public and private pumping wells tapping the groundwater aquifer. Over the last thirty years the withdrawals from the aquifer have increased. Another stress on the system is climate change leading to changes in precipitation and temperature conditions, which in turn affect aquifer recharge and the lake water budget. The effects of global warming are increasingly evident (IPCC 2014), and are expected to lead to an increase in the use of groundwater. A numerical groundwater flow model on the Bracciano lake and its hydrogeological basin was constructed using the finite-difference code MODFLOW2000. The model was implemented for steady state, at first and it was calibrated. After that, it was implemented for transient (monthly time steps over six years) conditions. A spatial interpolation of weather station information including rain and temperature (data over last 50 years), were considered as input values for the modelling of groundwater and lake water balance. The Bracciano model was applied to simulate possible climate change and water-use scenarios to better understand the behavior of an example volcanic lake under multiple stresses. The Bracciano model simulation results helps understanding the climate change effects on groundwater and lake water balance. It could also be a useful tool for analysing climate change adaptation strategies for water supply and groundwater and lake dependent ecosystems.