INTERACTION BETWEEN GROUNDWATER ANDSURFACE WATER THROUGH EL HAOUAREB DAM(Kairouan Plain, Central Tunisia)

摘要

The alluvial aquifer of the Kairouan Plain is the most important aquifer in thesemi-arid central Tunisia to provide the main water supply for agricultural and humanneeds. In 1989, the construction of the El Haouareb dam over a karstic sill completelychanged the aquifer recharge process. Prior to the dam construction, recharge camefrom the infi ltration of the Merguellil wadi fl oods in the plain and from the Ain elBeidha groundwater fl ow close to the dam site. Presently, recharge still comes from theAin el Beidha aquifer but also from the dam reservoir through karstic fi ssures.A detailed isotopic survey ( 18O, 2H, 3H, 13C, 14C) completed the hydrodynamicanalysis. The new recharge pattern is identifi ed and the progress of water infi ltratedafter 1989 is visible. Ratios of Ain el Beidha and dam waters in the karst or in the plainaquifer vary with time. A fi rst water budget is proposed for the period 1998–2000.