Structural assessment of Umm Lajj coastal area, Northwestern Saudi Arabia, using integrated aeromagnetic and gravity data: hydrogeological implications

This study focuses on the Umm Lajj region, situated along the eastern margin of the Red Sea, Northwest Saudi Arabia. The study integrates aeromagnetic and land gravity data to characterize subsurface geological structures influencing groundwater aquifers and their potential susceptibility to seawater intrusion. Data processing and interpretation were conducted employing a suite of filtering techniques to enhance data resolution and interpretability. A Butterworth filter was applied to distinguish between deep-seated and near-surface anomalies, while source edge detection and depth estimation methods were utilized to delineate structural features. The results reveal prominent NNW-, NW-, and NE-oriented fault systems, as well as associated grabens and horsts, which are structurally linked to Red Sea rifting processes. A significant structural basin was identified in the central coastal area and is interpreted as a potential groundwater aquifer. Gravity anomaly patterns also highlight low-density, fault-controlled zones that are likely conduits for seawater intrusion into the aquifer system. Conversely, NW-trending magmatic dikes and uplifted blocks along the western boundary may serve as partial barriers, restricting the lateral movement of seawater. The combined interpretation of magnetic and gravity data offers a detailed structural framework that enhances the understanding of regional hydrogeology and contributes to future groundwater resource management. These insights are particularly valuable for evaluating the risks of seawater intrusion and the vulnerability of groundwater systems in arid coastal settings.