CARACTERISATION DE LA NAPPE PROFONDE GAFSA NORD SUITE A LA SUREXPLOITATION DES EAUX SOUTERRAINES

Abstract

The system aquifer Gafsa North is powered mainly by the flood water of wad El Kbir and the infiltration of rainwater. This system suffers from overexploitation due to the development of phosphates sector and renovation of oases Gafsa which led to the realization of several deep wells. The present works aims to assess the quantitative and qualitative aspects of the deep aquifer Gafsa North following the excessive use of groundwater. The groundwater level has unveiled a drawdown that varies between 2 and 6 m. In this regard, the high decrease of piezometric level recorded especially in the downstream of the plain, shows the lack of natural recharge of the aquifer due to low rainfall events, and the increased use of groundwater. The hydrochemical study showed that salinity varies between 1 and 3 g/l. According to the diagram piper and lithological sections, that salinity is generated by the dissolution of calcium and sulphate minerals and does not seem to be affected by the conditions of exploitation.