Characterization of Al-Asfar Lake Region in Al-Hassa Oasis Using a 3D Gravity-Based Analysis

Abstract This study aims to investigate and reconstruct the 3D subsurface model of the Al-Hassa region, focusing on Al-Asfar Lake, a critical wetland shallow lake within the UNESCO-designated Al-Hassa Oasis. Primarily fed by agricultural drainage, Al-Asfar Lake influences the region's surface and groundwater systems. The objective is to characterize subsurface density variations and identify structural discontinuities, such as faults and fractures, impacting groundwater pathways and geological formations, providing essential insights for resource management and protection of this unique oasis and wetland ecosystem. A comprehensive gravity survey was conducted across the Al-Hassa region, specifically around Al-Asfar Lake, to map subsurface density variations and structural features influencing water flow and storage. Gravity measurements were taken on a structured grid and processed with corrections for terrain, drift, and instrumental noise to ensure data accuracy. Advanced modeling techniques generated a high-resolution 3D model, revealing lateral density contrasts and potential geological boundaries. This approach facilitates the identification of pathways and barriers to groundwater movement, yielding critical data for understanding hydrological processes that sustain Al-Asfar Lake and the broader Al-Hassa Oasis region. The gravity survey data revealed significant density variations across the study area, highlighting structural discontinuities likely associated with fault zones and fractures, which play a critical role in groundwater movement and distribution. These density contrasts identified areas of varying rock types and structural configurations, which are essential for understanding how subsurface features influence groundwater flow toward Al-Asfar Lake. The resulting 3D subsurface model offers a detailed view of hydrogeophysical dynamics, illustrating regions with varying groundwater storage potential. This model provides a valuable tool for assessing groundwater availability within the Al-Hassa Oasis ecosystem, supporting the sustainable management of Al-Asfar Lake. This study presents a novel application of gravity measurements for mapping hydrogeophysical features in Al-Hassa. By focusing on Al-Asfar Lake, the findings contribute to the knowledge of subsurface characterization, supporting groundwater management and preservation strategies in arid and agriculturally influenced environments.