Hydrogeophysical Characteristics of the Central Nile Delta Aquifer

The present study is carried out in Nile Delta aquifer, where the data of electrical resistivity and gamma ray logs of the 34 well ranging in depth between 80 and 140 m were used to calculate the aquifer parameters. It is aimed to estimate the spatial variability of the formation lithology, porosity, permeability, groundwater salinity, and the hydraulic conductivity. Bilqas Formation showed an increase in the thickness, porosity, and water salinity to the north and northeast directions. Permeability and hydraulic conductivity values decrease in the same direction. Bilqas Formation ranges in thickness from 3 m in the southwest direction to 31 m in the northeast direction. The shale content and porosity ranges are 54% to 97% and 21% to 55%, respectively. This layer has low values of permeability (16 × 10⁻⁹ to 78 × 10⁻⁹ mD) and hydraulic conductivity (<2 × 10⁻⁹ cm/s). The water salinity of this layer ranges from 200 mg to 1,600 mg/l.

In Mit Ghamr Formation, average shale content ranges from 4.5 to 22%. Numbers of scattered clay lenses are detected in different places with high intensity in the northeastern direction. Porosity ranges from 19 to 39%. High permeability values are recorded in this formation and ranged from 0.1 × 10⁻² to 8.7 × 10⁻² mD. The water salinity average values in this aquifer range from 220 mg to 2,100 mg/l. The calculated hydraulic conductivity values for this formation are of range 5.082 × 10⁻¹⁰ to 2.134 × 10⁻⁸ cm/s. In this layer, the increase in the shale content, the increase in porosity, decrease in the permeability and hydraulic conductivity, as well as the increase in salinity, are to the northern and northeastern directions.