Abstract
Arid coastal regions like Ras Gamila, Egypt, face pressing environmental challenges, including seawater intrusion, freshwater scarcity, and development pressures, which threaten their ecological and economic sustainability. This study bridges a critical research gap by developing an integrated framework that links subsurface geophysical stability with surface environmental conditions to guide eco-development. We employed a multi-method approach, combining vertical electrical sounding (VES), time-domain electromagnetic (TDEM) soundings, shallow seismic reflection, soil radon analysis, and spatial data from digital elevation models (DEMs), shoreline dynamics, and climatological factors. Our results delineate a critical freshwater-bearing Nubian sandstone aquifer (19-94 m thick, resistivity: 228-302.5 Ωm) and identify significant seawater intrusion (resistivity: 1.1-2.5 Ωm). A novel sustainability matrix, integrating these diverse datasets, classifies the region into three distinct zones: high-sustainability inland areas (35-45% of the region) suitable for immediate development, moderate-sustainability central zones (35-45%) requiring targeted improvements, and low-sustainability coastal areas (25-30%) necessitating restoration and protection. The findings provide a scalable, geophysically-informed model for sustainable planning in arid coasts, directly supporting United Nations Sustainable Development Goals (SDGs) 6 (Clean Water) and 13 (Climate Action) by offering a science-based strategy for balancing economic growth with environmental conservation.