Geophysical and multi-criteria decision methods for delineating groundwater potential in coastal terrains: a study from Port Sudan

Groundwater resources in arid, semi-arid, and coastal regions are of vital importance due to the scarcity or complete absence of reliable surface water sources. Port Sudan city is now serving as the administrative capital following the country's political instability. As a result, the city has witnessed a massive influx of internally displaced people, placing pressure on its already fragile water resources. The region is underlain by Precambrian basement terrains, restricting groundwater occurrence to structurally controlled aquifers and alluvial deposits. This study integrates gravity data analysis with the analytical hierarchy process (AHP) to delineate potential groundwater zones in the area. Structural features were extracted from gravity data using edge detection techniques, including vertical and horizontal derivatives, tilt angle derivative, and analytical signal. A density map of the identified structures was generated and integrated with other groundwater recharge-controlling factors including geology, rainfall, land use, slope, and drainage density within an AHP framework. The multi-criteria evaluation resulted in a groundwater potential map delineating three distinct zones: low (41.5%), moderate (13%), and high potential (45.5%). These zones were validated using 2D gravity inverse modeling constrained by boreholes data along two profiles. This integrated approach provided a preliminary yet effective tool for groundwater exploration in complex basement terrains and supports decision-making for further detailed hydrogeological and geophysical investigations in Port Sudan and similar arid environments. Incorporating more detailed geophysical analyses could further enhance subsurface characterization and improve groundwater potential assessments.