Hydro-geophysical study in Al-Khogalab basement-sedimentary basin transition area using Vertical Electrical Sounding method, Khartoum State, Central Sudan

Abstract

Groundwater represents the available source of fresh water in the northeastern part of Khartoum State for drinking as well as for irrigation purposes. The objective of this study involves the assessment of the occurrence and potentiality of the groundwater in order to meet the increasing demand of water. The adopted methodology involves the digital processing of Landsat 8 OLI image and geophysical vertical electrical sounding (VES). VES data was processed and interpreted with the aid of IP2WIN computer Software. The outcome of the present study showed that the area is located in the transition zone between the basement and sedimentary terrains. The River Nile represents the main source of groundwater recharge from W and SW directions, with minor recharge source from the direct precipitations and seasonal valleys for the shallow groundwater aquifers. The depths to the basement vary from that basement exposed at the surface to more than 200m a.s.l. at the western part of the area. The very high resistivity values (>400 ohm/m) reflects the hard basement rocks, the high values (250-400 ohm/m) were interpreted as dry soils and gravels, while low resistivity values (<250 ohm/m) are related to sedimentary rocks. The conducted geo-electrical resistivity survey indicated that the basement exposed at the ground surface at the central part of the study area, while the considerable thickness of sedimentary rocks in the eastern and the western side of the area is preserved as a result of structural faulting. In term of sedimentary thickness and the recharge source, the western part of the area is considered the most potential zone for groundwater occurrence.