Tracing of the defunct Canopic Nile branch using geoelectrical resistivity data around Itay El-Baroud area, Nile Delta, Egypt

Abstract

Around the Nile Delta Branches, ancient settlements had been created and left their remains to be good witness for the paleoenvironment during the Holocene time. Therefore, tracing of the defunct Canopic branch and its distributaries as well as associated environments are of great importance. Using a Schlumberger electrode configuration, well-distributed 44 vertical electrical resistivity soundings were acquired. The 1D modelling technique was applied to estimate the depth and the apparent resistivity of the interpreted geoelectrical units. Then 2D inversion was applied for the same data set using the ABIC least-squares inversion scheme. The geoelectrical cross-sections and slice maps discriminate the Upper Quaternary sequence into three geoelectrical units. The Holocene Nile mud is represented by two units: the agricultural root zone (unit 1) that is underlain by relatively thick water-saturated mud (unit 2). The Upper Pleistocene sandy aquifer is represented by irregular surface (unit 3). Two generations of defunct channels were traced out. The older channels are characterized by low sinuosity compared with younger channels. This is probably attributed to river activity due to relatively low sea level and much higher Nile discharge. The system of younger channels is characterized by broad meanders, probably as a consequence of sea-level rise and decreased gradient since the Middle Holocene. © 2011 Nanjing Geophysical Research Institute.