THE AQUIFER OF TURONIAN LIMESTONES (TADLA BASIN, MOROCCO) - LOCAL ANDREMOTE GROUNDWATER RECHARGE FROM THE ATLAS

The Tadla basin is situated to the south of the Moroccan Meseta; it is limited by the overlapping north Atlas rocks and contains an importan t aquifer within the Turonian limestones. The unconfined ground water to the north becomes confined to the south. The piezometric map shows that the flows converge towards the Wadi Tessaout downgradient followi ng a large NE-SW drainage axis which represents a highly permeable zon e. The water flow and the environmental isotopes show that the Turonia n is supplied at the same time from both the outcrop of the 'plateau d es phosphates' to the north and the Atlas aquifers to the east. The dr ainage axis represents a mixing zone. Hydrometric monitoring of the sp rings of the Wadi Tessaout downgradient, and their hydrochemical and i sotopic characteristics, shows that they are common outlets of Miocene -Pliocene-Quaternary and Turonian aquifers.