Methodology to Evaluate Aquifers Water Budget Alteration Due to Climate Change Impact on the Snow Fraction

This paper aims to propose a methodology to evaluate and quantify perturbed groundwater budgets considering the projected reduction of Average Snow Fraction of Surface Runoff (ASFSR). Future groundwater budgets are generated considering different CC temporal Scenarios, RCMs, as well as the status of each Groundwater Body (GwB). The proposed methodology is applied to the Central Mountain Range of Iberian Peninsula (Avila Province). Existing studies show a drastic Reduction on Snow Melting (RSM) and on Cumulative Snow Volume (CSV). This leads to a huge reduction of Average Snow Fraction of Surface Runoff (ASFSR) and on groundwater availability calculated through the indicator Perturbed Exploitation Index (PEI). There are important differences depending on the RCM used, on the temporal CC Scenario and on the GwB considered. Main difficulties and challenges comprise the lack of field data and rigorous studies on modelling of groundwater hydrodynamic modelling. Despite of that, research results show a robust and generalized increase in all Exploitation Indexes (EI). EI increase is of 4.17 % for IP1 (Short Term) RCP 4.5, 14.94 % for IP2 (Medium Term) RCP 4.5, 17.65 % for IP3 (Long Term) RCP 4.5. On the other hand, there is an increase of 9.89 % for IP1 RCP 8.5, 19.05 % for IP2 RCP 8.5 and 35.14 % for IP3 RCP 8.5. Thus, there is a generalised and very important decrease of recharge (PARR) of 59.03 % for IP1 RCP 4.5, 88.97 % for IP2 RCP 4.5, 90.02 % for IP3. Likewise, for RCP 8.5, there is a decrease of 72.69 % for IP1 RCP 8.5, 88.97 % for IP2 RCP 8.5 and 97.90 % for IP3.