Seawater Intrusion in the Coastal Aquifers of Lebanon: the Importance of Reducing the Anthropogenic Factors.

Patterns of seawater intrusion (SWI) over most of the coastal aquifers in Lebanon have been noticed since more than 5 decades. This hazard is now assessed over the entire Lebanese coast through field measurements and sampling of available groundwater resources. The results show elevated salt content present in several zones and ongoing salinization to variable extents in others. Porous non-consolidated aquifers show the most permanent and growing patterns of SWI along the coast, while fractured and karstic aquifers appear to be more resistant to the intrusion spread. Comparison with previous SWI studies confirms early salinization signs detected at several points of the coast, and well-established salinization over the recent years in many other coastal zones.

The largest impact on SWI comes from a mix of anthropogenic factors essentially related to urbanization including change in land use, modification of natural flow, along with growth in excessive groundwater abstractions related to a failing water-resources development and management. For example, flood control and land management plans of two major coastal rivers implemented since the 1960s are now associated with two of the sharpest SWI patterns of the entire coast. Climate-related and other natural SWI drivers do not appear to play important roles in the observed coastal groundwater salinization so far. However, integrated water resources management covering the entire watersheds of coastal river basins and aquifers is needed to forecast and mitigate longer term climatic effects especially those related to the snowmelt driven recharge of more inland aquifers and the availability of water resources outside the coastal aquifer areas. Mitigating SWI hazard at national scale requires 1) appropriate policy for water resources management to be adopted at national governmental level, 2) continuous awareness and education campaigns on water resources and water use, 3) implementing a monitoring plan for groundwater quality in all coastal aquifers and 4) undertaking detail hydrogeological studies in key coastal areas to better understand the mechanisms and amplitude of seawater intrusion.      

Reference: Ata Elias, Wisam M. Khadra & Michel A. Majdalani (2025) Saltwater intrusion in coastal Lebanon: evolution of patterns, and database for groundwater quality monitoring and management, Hydrological Sciences Journal, 70:6, 975-993, DOI: 10.1080/02626667.2025.2468839