Geochemical controls of groundwaters upwelling in saline environments: Case study the discharge playa of Sidi El Hani (Sahel, Tunisia)

Within the discharge playa of Sidi El Hani, the surrounding aquifers converge due to uprising underground waters. The Principal Component Analysis proves that the fluid density is inversely influenced by the rainfall and has a reciprocal effect with evaporation. This parameter is governed by uprising groundwaters and the convergence of waters and inflow in the sabkha result in a geochemical exceptionality. The fluid density maintains high values during the year, the modeling of which shows a third sinusoidal distribution. This model remains stable along a span of time because the surrounding aquifer feeds the discharge playa by a continuous salty water flow. In general, waters in the majority of drills surrounding the discharge playa have the same facies which is mainly made up of water charged with Na+ and Cl-. A sample from the northeast of discharge playa shows a geochemical similarity with two wells located in its vicinity.