Investigating seawater intrusion and salinization using the integration of hydrochemical and geoelectrical techniques

Abstract

Seawater intrusion poses a significant environmental threat to water resources, agriculture, and ecosystems. We investigate the extent of seawater intrusion and salinization in the eastern coastal aquifers of Saudi Arabia. Hydrochemical measurements and electrical resistivity tomography (ERT) techniques are used to assess groundwater quality and the subsurface extension of seawater intrusion. Two resistivity profiles, 475 m long each, are analyzed to gain insights into the subsurface geology and seawater intrusion. The inversion of the recorded resistivity data reveal four distinct subsurface layers. The uppermost layer consists of surficial deposits, followed by a sandy seawater intrusion layer, beneath which lies a marl layer, and at the bottom, a dolomitic limestone layer representing the brackish-water aquifer. The ERT results are integrated with hydrochemical and hydrogeologic results from 12 wells to overcome the limitations of the ERT. The findings of this study would facilitate the development of efficient mitigation strategies and sustainable management of the groundwater resources in the study area or similar coastal regions affected by seawater intrusion. Understanding and delineating the boundary between saline and fresh water is crucial for safeguarding water resources for agricultural purposes, preserving ecosystem health, and ensuring the long-term sustainability of water supplies in coastal areas.