Application of the "ERAS" model to estimate aquifer recharge time series and their relation to climate change in four karstic aquifers from the High Vinalopo County (Alicante)

This study supposes a first step to evaluate the effects of the climatic change (CC) on the natural recharge of aquifers. To estimate the recharge a unicellular deposit type mathematical model has been used. It reproduces the recharge-exploitation-evolution of piezometric heads phenomenon with a monthly time step. The initial data are rainfall, temperature, abstractions and heads. The main advantage of the model is its independence of the mechanism of water displacement on the ground and in the unsaturated zone. Four overexploited karstic acuifers in the High Vinalopo County (Alicante) have been selected. Annual recharge time series for the 20th century have been made and grouped into decades they show a logarithmic decreasing tendency in the four aquifers. This fact is due to a decreasing trend of the annual rainfall and an increasing trend of the temperature, observed by means of the Spearman correlation test. The percentage of recharge on total rainfall also follows a significantly decreasing tendency in all cases. Therefore, relative recharge is progressively reduced along the century following a rainfall decrease and a tempeature increase. The main conclusion of the study is that the ERAS model (Estimation of Recharge in Overexploited Aquifers) has been shown to be efficient to estimate the natural recharge in karstic aquifers and so it is valid for simulating future conditions from CC prediction models. It remains for the future to reduce the temporary scale to hourly level to integrate in the analysis the effect due to rainfall intensity.