Coastal aquifers worldwide confront significant challenges from salinization, with seawater intrusion (SWI) particularly severe in urbanized coastal areas. The Nile Delta Aquifer (NDA), a crucial coastal resource, is notably affected by SWI, especially in its central regions, underscoring the need for comprehensive assessment and monitoring frameworks. This chapter reviews the impacts of sea level rise (SLR) and SWI on the NDA, offering an overview of salinity sources in coastal aquifers and evaluating previous numerical modeling studies related to SWI in this area. It also examines the potential impacts of climate change. A central focus is integrating hydrogeochemical and geophysical methods to characterize the freshwater-saltwater interface accurately. This study employs high-resolution vertical electrical resistivity surveys alongside extensive hydrogeochemical analysis, including major ion chemistry, stable isotope analysis, and geochemical modeling. The findings from this interdisciplinary approach provide valuable insights for developing sustainable groundwater management strategies aimed at mitigating the impacts of SWI and ensuring the long-term availability of freshwater resources in the Nile Delta region. The chapter concludes with a discussion of the research implications and outlines potential future directions for addressing this critical environmental challenge.