Analysis and Remediation of the Salinized, Damour Coastal (Dolomitic) Limestone Aquifer in Lebanon

Abstract

Coastal aquifer management has recently emerged as a main scope in groundwater hydrology, especially in arid and semi-arid zones. About two thirds of the human population are currently gathered close to shorelines relying on coastal groundwater resources. Worldwide, these systems are subject to quality deterioration due to a multitude of anthropogenic impacts and subsequent saltwater intrusion (SWI).
Many hydrological and hydrochemical features of SWI have been disclosed during the past century through numerous case studies, column studies, scale models, flow and reactive transport modeling. Yet, many scientific and engineering challenges remain, some of which need to be addressed for a better prospecting of future coastal freshwater reserves. The scope of this thesis is to contribute to the analysis and remediation of SWI by studying the following aspects: (1) response of carbonate aquifers with varying Ca/Mg content to SWI, (2) behavior of trace elements (TEs) where fresh and intruded seawater mix, (3) derivation of groundwater baseline levels in polluted settings, notably salinized aquifers, (4) identification and quantification of major hydrogeochemical processes stimulated by SWI, (5) reliability of complex models (especially in karst) with variable-density and solute transport formulations, and (6) feasibility of SWI mitigation strategies.
In order to reach the scope, some existing tools have been adapted and new tools developed. All together, they offer an interesting toolbox for investigating SWI anywhere. They were successfully applied to a stressed dolomitic limestone aquifer system in Lebanon (Eastern Mediterranean), suffering from salinization and other minor anthropogenic impacts.