Groundwater Recharge of the Kairouan Plain Aquifer: Evidence of Preferential Flow Paths Through the El Haouareb Limestones?

Groundwater is a key component for the development of semi-arid areas where surface water resources are scarce. Water managers need knowledge about water reserves to cope with their multiple constraints. In the Merguellil basin (Central Tunisia), the Kairouan plain aquifer supplies water for a rapidly growing irrigated agriculture economy but recharge processes are still poorly known. The present paper investigates groundwater transfers from upstream aquifers to the Kairouan plain through the hydraulic threshold of El Haouareb. A conceptual geological 3D model based on lithologs analyses was built. Two steady state groundwater models were run using Feflow code in high and low flow conditions. Results suggest that the limestone aquifer that ensures hydraulic connectivity between the upstream and downstream aquifers behaves like a dual-porosity medium with highly significant preferential groundwater flow paths and cannot be simulated as an equivalent porous media.