Isotopic and Chemical Study shows the contribution of Nadhour-Saouaf Groundwater to the recharge of Sisseb Groundwater (Centre of Tunisia)

The aquifer system of Nadhour-Saouaf located at the North of the basin of Sisseb El Alem is one of the most significant groundwater systems, which contribute to recharge the aquifer system of Sisseb, located at the centre of the study basin. However, the lakes and the dams that were carried out in the Eighties and especially in the Nineties mobilized most of the surface waters which recharged the aquifer of Sisseb. In spite of the effect of these managements on the functioning of these aquifers, the role of Nadhour-Saouaf groundwater in the recharge of the aquifer of Sisseb is still significant. This contribution was proven by the piezometric level regression, which varies between 100m in the North of Nadhour-Saouaf and 30m in the South of Sisseb. The communication between these two aquifers systems was confirmed by the results of the hydrochemical analyses. Indeed, the aquifers systems of Nadhour-Saouaf and Sisseb are homogeneous and are characterized by water with chlorinated-Sulphate facies. The salinity of water, increase with the direction of flow since the basin of Nadhour-Saouaf to wards the basin of Sisseb. Moreover, the carbon-14 activities distribution proves the contribution of the Nadhour-Saouaf aquifer system to recharge of the aquifer system of Sisseb and the refill area are located in the western part of the basin