Impact of water resources management on groundwater hydrochemical changes: case of Grombalia shallow aquifer, NE of Tunisia

Grombalia region (NE Tunisia) exploits multiple sources of water: groundwater from shallow and deep aquifers, local surface water, and external surface water transferred from the North-west of Tunisia (Medjerda River and Ichkeul basin). The coordinated control of the water sources is very week while no evaluation of the impact of anthropogenic activities on groundwater resources was carried out so far. The present study use water-level time series, rainfall, and groundwater extraction data to identify the piezometric changes. Geochemical data were used to characterize and classify water samples and to study water-rock interaction based on ion plots and diagrams, mineralization, and nitrate contamination processes, as well as their fate and origins. The lack of regulation of the water use is potentially responsible of the increase of both level and salinity of groundwater in the central and downstream parts of the basin and of a large groundwater drawdown in the upstream region.