Integration of ERT and shallow seismic refraction for geotechnical investigation on El-Alamein Hotel Building Area, El-Alamein new city, Egypt

El-Alamein new city is regarded as one of the iconic cities of the Egyptian North Western Coast to be not only residential units but also summer resorts for tourist attractions. This study examines the efficiency of integrating geophysical methods for determining if clay lenses exist or seawater has intruded into shallow strata and for calculating the geotechnical parameters of near-surface layers for construction purposes. Nine electrical resistivity tomography (ERT) and shallow seismic refraction (SSR) profiles are conducted in this study. From ERT data, we observed the intrusion of seawater in layers at different depths. From SSR data, two layers are observed along profiles, while three layers are observed along the other profiles according to their velocities. Near-surface geotechnical parameters, that were calculated from SSR data, are integrated to evaluate our study area. Accordingly, it was considered a low-competent area and suitable for buildings with low heights, and the only difference is the intrusion of seawater, therefore, it is subdivided into 2 zones. In zone (A), the second layer is used as a foundation layer. Zone (B) is pretentious by the intrusion of seawater, and it is not suggested to construct any buildings or to improve the strength of concrete exposed to seawater in this zone to be suitable also for buildings with a low height. Geophysical methods (Nine profiles of ERT and (SSR) were used in El-Alamein new city to assess clay lenses and seawater intrusion for construction purposes.Seawater intrusion and varying layers were observed at different depths, influencing the geotechnical parameters and subdivision of the study area.The second layer in the study area was subdivided into two zones, one is suitable for foundation, while another is affected by seawater intrusion and not recommended for construction or using concrete exposed to seawater.