Hydrogeophysical investigations at El-Nubariya-Wadi El-Natrun area, west nile delta, Egypt

Abstract

Establishing new communities is one of the strategic plans of the Egyptian government during the last decades. One of the targeted localities for such plan is the West Nile Delta area where it is considered as a promising area for creating new settlements. The area under investigation is located to the west of Nile Delta on both sides of the Cairo-Alexandria desert road, between latitudes 30° 17′ and 30° 42′ N and longitudes 30° 00′ and 30° 30′ E. It covers an area of about 1,825 km2. To help such national plan, the present study aims to delineate the hydrogeological regime of the study area through qualitative and quantitative interpretation of the available electrical and electromagnetic data. The geoelectric resistivity survey includes 93 vertical electrical soundings (VES) carried out using Schlumberger array with AB/2 ranging from 1.5 m up to 700 m in successive steps. The time domain electromagnetic (TEM) survey was executed near selected VESes where 26 TEM stations with loop spreading 50 × 50 m were measured. The quantitative interpretation was conducted through one-dimensional resistivity inversion for both VES and TEM data using the software IX1D from Interpex Ltd. Ten cross sections (from VES data) and three cross sections (from TEM data) were constructed and well correlated with the available boreholes. The cross sections reveal that the depth to the main aquifer ranges from 6 m at the northern part near El-Nubariya city to about 90 m at the southern part. On the other hand, the aquifer system in the area is divided into Pleistocene and Pliocene aquifers. The Pleistocene aquifer which is the shallower aquifer is consisted of gravelly to clayey sand deposits. The Pliocene aquifer, deeper, is the main aquifer and composed of sand to gravelly sand deposits where in some places, it can be divided into two aquifers. Based on the inferred structural map, it is worth to mention that Wadi El-Natrun and its lakes are structurally controlled by faulting systems trending NW direction.