Impact of groundwater flow across tectonic aquifer compartments in a Miocene sandstone aquifer: three-dimensional hydrogeological modeling of the Kasserine aquifer system in central Tunisia and northeastern Algeria

Abstract

The Kasserine Aquifer System (KAS) is a transboundary aquifer, located in an arid region in central Tunisia and extending into northeastern Algeria. The system consists of four compartments: Oum Ali-Thelepte, Feriana-Skhirat, and the Plateau and the Plaine of Kasserine. The challenge of this study was to evaluate the influence of regional faults on groundwater flow in the different compartments of the KAS and to estimate the regional impact of current and future groundwater use. A three-dimensional saturated regional groundwater flow model for the steady state and transient conditions (1980–2015) was created and calibrated. This work was achieved using numerical flow modelling, coupled with geological modelling, using FEFLOW and GeoModeller software. The significance of regional faults as potential barriers or conduits to groundwater flow in the different aquifer compartments was evaluated by considering the different recharge rates. Two connectivity hypotheses were proposed at each major fault, and the general hydraulic relationship of units that are juxtaposed by each fault were considered. This study contributes rigorous estimates for the diffuse and concentrated recharge in the arid study region, and evaluates the groundwater behavior that shows a gradual decline in the water table over time, using a regional model. Different predicted outcomes for the KAS based on variable potential groundwater extraction scenarios for the period 2015–2050 have been developed. The results of numerical simulation provide useful information regarding the behavior of the KAS aquifers, and contribute significant knowledge to guide sustainable practice for present and future groundwater management.