Vulnerability Assessment of Coastal Aquifers to Seawater Intrusion under Anthropogenic Pressures: A Case Study of the Eastern Mitidja Plain

The alluvial plain of Mitidja, considered the largest aquifer in northern Algeria, is a strategic zone for freshwater supply, serving domestic, industrial, and agricultural needs. However, this resource is increasingly vulnerable due to anthropogenic pressures such as intensive groundwater abstraction, dam construction, and rapid urbanization. The Eastern Mitidja aquifer, which is in direct contact with the Mediterranean Sea, is particularly exposed to seawater intrusion, threatening groundwater quality. While the GALDIT method has been applied to several Algerian aquifers, it has not yet been used for the Eastern Mitidja sector. The objective of this study is therefore to assess the vulnerability of this specific aquifer to seawater intrusion using the GALDIT model combined with Geographic Information Systems (GIS). The results reveal a significantly higher risk of seawater intrusion in the downstream section of the aquifer, while the upstream zone remains relatively unaffected. These findings provide a first baseline vulnerability map that can support local groundwater management and help prioritize areas for monitoring and intervention.