3D simulation of a multi-stressed coastal aquifer, northeast of Tunisia: salt transport processes and remediation scenarios

A salinization of groundwater by oilfield brine and seawater intrusion was detected in the plain of Wadi Al Ayn and Darouda in CapBon, northeast of Tunisia. The objective of this work is to simulate the historical trends of saltwater distribution in the study area and to predict its future dynamics under some proposed countermeasures for remediation. Based on the developed model with SEAWAT, the oilfield brine plume needs at least 5 years to be naturally reduced to less than the half of its actual size, while the seawater-freshwater interface can reach an inland extent of 1.3 km with a TDS of 10 g/L if no countermeasures will be taken until the next three decades. The tested remediation plan by model demonstrated that the artificial recharge with treated wastewater is the best solution to stop seawater intrusion just after 2 years of percolating 1 m/day with TDS of 1.5 g/L of recharge water. The natural remediation of the oilfield brine plume can be enhanced by imposing optimized pumping rates and installation of a restricted pumping perimeter.