GEOELECTRICAL RESISTIVITY AND HYDROGEOCHEMICAL INVESTIGATIONS AT ABOU KEBIR -HIHYA DISTRICT, EAST NILE DELTA, EGYPT

Forty one vertical electrical soundings (VES) using Schlumberger electrode configuration have been conducted at Abu Kebir–Hihya district, East Nile Delta. Moreover, seventeen representative water samples from the Quaternary aquifer have been collected and chemically analyzed for the major cations and anions to correlate the effect of the ionic content on the measured resistivity. Information from boreholes in this area of the east Nile Delta has guided the interpretation. The results of the VES data interpretation have been displayed in a form of geoelectric cross-sections; resistivity slices maps. Hydrochemistry sections also are constructed. Inspections of the geoelectric cross sections reveal clearly the lithostratigraphy and the paletopography of the Late Quaternary at this part of East Nile Delta. The calculation of slice resistivity maps at selected interval depths leads to tracing of several subtle anomalies and to shed new lights on the migration and origin of these resistivity anomalies. The constructed interpreted resistivity sections revealed that the main sandy aquifer is overlain generally by a thin clayey cap. Thus in the areas of reduced thickness of the clay cap, contamination of the sandy aquifer could be direct. The contamination of this main aquifer is confirmed by the results of the hydrochemistry data, where the samples collected from the site of big villages exhibit the maximum recorded values of total dissolved solids (TDS). Also, it is found that the resistivity of the Pleistocene sandy aquifer is generally controlled by ionic content distribution. Moreover, some parts of the ancient Nile delta branches, which were crossing within the study area, have been delineated along the constructed geoelectric profiles. The inferred parts are belonging to what is called Pelusiac and Tanitic Nile Delta branches. Keywords: Nile Delta, Vertical Electrical Soundings, Hydrochemistry, Quaternary aquifer, Buried channels, Archaeology, Environmental geophysics.