Estimation of quantitative descriptors of northeastern Mediterranean karst behavior: multiparametric study and local validation of the Siou-Blanc massif (Toulon, France)

Key parameters controlling the recharge and behavior of Mediterranean karsts were selected in order to make a quantitative description of northeastern Mediterranean karsts on a regional scale. The methodology was applied to an actual karstic aquifer on the Siou-Blanc Plateau (France). For the recharge study, it was observed that the average yearly rainfall value and delta O-18 measurements in springs can be considered as good descriptors of climatic variations observed in the Mediterranean area. They can be used to estimate the intake area and the infiltration coefficient. A comparison with a numerical (double permeability) flow model (MODFLOW) on the Siou-Blanc karst improves these exponential relations between effective rainfall and delta O-18 measurements. Infiltrated water, which flows though different rock types, induces contrasts in the water chemistry. An instantaneous physical and chemical analysis of all the springs of the Siou-Blanc aquifer displays the same expected functioning and variations as had been forecast using the conceptual scheme. Thus, it can be applied to wide areas associated with a northeastern Mediterranean climate for a first approach of a karst study; such a model enables a useful estimation of recharge and behavior with few simple data.