Coastal Soil Characterization Using Remote Sensing, Geoelectrical and Borehole Data: Insights from Nile Delta Coast, Egypt

Summary Costal soil characterization has a great significance in environmental and engineering studies. The present work is a proposed protocol using remote sensing (RS), direct current resistivity (DCR) and time-domain induced polarization (TDIP) data for characterizing the coastal soil on the Nile Delta coast. The land use-land cover (LU-LC) is introduced to get the changes in land degradation over the selected analysis period. Considering RS data analysis, geoelectrical measurements are carried out. Regarding to the saltwater intrusion and other heavy anthropogenic activities along the coastal zones, it can be noticed that the lateral heterogeneities within the near-surface coastal soil cannot be characterized using individual DCR data. The 2D resistivity profiles show limitations in mapping the high conductive layers of smearing and amplification of the conductive layer boundaries. On the other hand, the 2D-TDIP images can differentiate between the high conductive layer and saltwater intrusion calibrating with the nearby borehole data. Interestingly, negative chargeability data has been reported for coastal clays. Finally, the electric cone penetration test (CPT) with pore pressure measurements is carried out to confirm and calibrate the geophysical inversion results. The success of the proposed approach supports further studies into understating the geotechnical properties in such coastal areas.