Geological mapping of the Central Cairo-Suez District of Egypt, using space-borne optical and radar dataset

Abstract

The Central Cairo-Suez District (CCSD) has a special urban extension, particularly the fast growth of the new Cairo and New Administration Capital of Egypt (NACE). Accurate discrimination of the lithology and surface and near-surface structures will be a valuable contribution to the geotechnical characterization of the foundation rocks and geohazards. The present work utilizes remote sensing datasets; including Phased Array L-band Synthetic Aperture Radar (PALSAR-2) scenes, Landsat-8 OLI/TIRS data and high-resolution images of Google Earth accompanied with field work to update the geological map and highlighting the information on the spatial lithological distribution and the faulting history of the CCSD. Radar data is utilized to make use of its penetration capabilities to image the possible near-surface structures and rock contacts. The PALSAR-2 data improved the surface and shallow structural imaging around Gebel Oweibed and in other selected subsets. The NW-striking shear faults in Quaternary sediments were recognized for the first time. Their recent activation has been proved by the recent seismic events. The False Color Composites (FCC), Band ratios (BR), Decorrelation Stretch (DS) image processing techniques have been successfully applied to differentiate between sandstones, shales, marls, carbonates, basalts, and gravels which represent eight lithological units of Middle Eocene to Quaternary time. The results were enhanced and mapped by supervised classification with accuracy assessment exceeding 88%. Integration of remote sensing data, previous mapping, and field check resulted in a more accurate mapping of the study area with new important modifications.