Geoleectrical and geochemical studies for groundwater evaluation in el-Gabel el-Asfar area and its vicinities, Nile delta, Egypt

Abstract EN

The present work deals with the delineation of the water-bearing horizons through geoelectrical investigation as well as evaluation of groundwater quality through the hydro chemical analyses.

This would provide the scientific basis required for launching the proposed drinking water plant.

The field work included carrying out 16-vertical electrical soundings and measuring two imaging profiles.

Also, 50-groundwater samples, three reference surface water samples and three sewage water samples representing the common drains were collected.

The results showed that the subsurface succession consists of four geoelectrical zones (A, B, C and D). Zone A is dry, while zones B, C and part of zone Dare water bearing.

Generally, the resistivity values of these zones increase westward and decrease downward due to the increase of groundwater salinity as well as the presence of clay intercalations.

By comparison between the geoelectrical and the hydro geochemical studies in the study area, it is clear that the Quaternary aquifer (Zone B) is clearly distinguished into upper and lower parts with a groundwater salinity varying between 263 mg / l and 960 Mg / l reflecting fresh water and is mainly characterized by HCO3–Na water type, while that of Miocene groundwater (Zone C) ranges from 1056 mg / l to 2764 mg / l reflecting slightly brackish water and is characterized by Cl–Na water type.

Generally, groundwater salinity increases from west to east.

The Quaternary aquifer is chemically polluted as the detected constituents exceed the standard limits, representing a heavy hygienic threat, whereas the Miocene aquifer is mainly safe.

Groundwater quality was evaluated for different uses and some recommendations were given.