Groundwater monitoring for assessing artificial recharge in the Mediterranean coastal aquifer of Korba (Northeastern Tunisia)

Groundwater (GW) artificial recharge with treated wastewater (TWW) is seen as a promising technical solution to overcome groundwater overexploitation and seawater intrusion and to ascertain future water resources availability. While these introduced recharge systems have shown positive impacts in many areas across the world, their effective contribution to GW recharge is still not well quantified in water-stressed regions such as Tunisia. The scarcity of on-site data with accurate temporal and spatial measurements and resolution in such areas hinders the clear assessment of these recharge systems’ performances. This article presents an approach based on the on-site monitoring of groundwater level and salinity measurements and recharge rate records spanning over the 6-year period to investigate the performances of a wastewater-based recharge system located in the Korba-El Mida site in Tunisia. The analysis showed that the artificial recharge did not have an impact on groundwater level. Controversially, a decrease in water salinity in and around the study site was observed. Findings emphasize on the weak wastewater volumes applied to the recharge system and the clogging phenomena that occurred in the pool and in the vadose zone. Furthermore, analyzing the information over a short period of time could be misleading as the results of a 6-year period of monitoring show clearly that the way the site was managed and the local conditions have a role in understanding and interpreting the results even if the artificial recharge was appropriately designed.