Seawater Intrusion Mapping Using Geophysical Methods, Piezometry, and Hydrochemical Data Analysis: Application in the Coastal Aquifer of Nador Wadi Plain in Tipaza (Algeria)

Nowadays the salinization of freshwater resources due to seawater intrusion represent a worldwide issue. Accordingly, this study aims to identify and locate the freshwater-saltwater interface in the downstream part of the Nador wadi plain (Algeria), a coastal area characterized by a semi-arid mediterranean climate using a multi-methodologies approach including geophysical methods, hydrostatics approach, hydrochemical method, and piezometry situation. The investigation was carried out by the electrical survey and refraction seismic methods in the period of April-May 2018. Moreover, the hydrochemical and piezometry methods were used to confirm the results of the geophysical technique. The results of the present study case showed that the seawater intrusion interface is located at 420–1380 m from the shoreline. Additionally, the presence of the bedrock bulge (clay formation) at a distance ranging between 550 and 1050 m from the shoreline, plays the role of the natural hydraulic barrier for the seawater advance. The findings indicate that the identified seawater intrusion interface and the natural hydraulic barrier formed by the bedrock bulge are critical for managing groundwater resources in the Nador wadi plain. This methodology can be applied to other coastal plains worldwide to address the challenges of seawater intrusion and groundwater salinization.