Assessing coastal aquifer vulnerability to seawater intrusion: adaptation of the DCG method and application to the Dradère–Souière coastal aquifer in northern Morocco

Abstract

Context Seawater intrusion into coastal aquifers represents a major global environmental challenge, leading to salinisation of these water resources. Aims This study aims to protect coastal aquifers from marine salinisation by assessing their vulnerability to seawater intrusion. Methods The DCG method was adapted by considering the weighted sum of the following three critical parameters controlling seawater intrusion: distance from saltwater (D), aquifer hydraulic conductivity (C) and the hydraulic gradient (G). Thereby, the weights assigned to these parameters were objectively determined through sensitivity tests. Key results The DCG map of the Dradère–Souière coastal aquifer shows that vulnerability increases near the sea, with a high to extreme vulnerability zone extending parallel to the coastline up to 5000 m inland. These findings are corroborated by a correlation analysis with the electrical conductivity map. Conclusion This study highlighted the adaptation of the DCG method for assessing the vulnerability of coastal aquifers to seawater intrusion and its successful application to the Dradère–Souière coastal aquifer. Implications The DCG method could be extended to other coastal regions as a strategic tool for protecting against seawater intrusion. Further improvements could be achieved by correlating it with other approaches and integrating it with GIS technologies.