Abstract:
Geophysical investigation using Vertical Electrical Sounding (VES) method was conducted to
investigate groundwater potential zone for Debre Tabor town at Ribb catchment and South Gondar
Zone, North Ethiopia. The main objective of this study was to investigate Groundwater potential using
vertical electrical resistivity method at Ribb catchment for Debre Tabor town.The aquifer system of
the catchment is multi-layer aquifer as observed from the interpreted conducted VES points.
Hydrogeological site delineation carried out and then geophysical investigation conducted
specifically Vertical Electrical Sounding (VES) method. The data acquired from sixteen (16) VES
points using Schlumberger electrode arrays with maximum half current electrode spacing
(AB/2=500m).
The qualitative analysis of VES data was carried out by using pseudo depth sections and different
Geoelectrical sections. The quantitative interpretations of the Vertical Electrical Sounding data were
conducted by modeling the Vertical Electrical Sounding data using Ipi2win software and constructing
geoelectric sections along selected survey lines, using the result from individual Vertical Electrical
Sounding point interpretations. The Vertical Electrical Sounding results of the data revealed three main
geoelectric layers which differ in degree of weathering, fracturing, composition and depth of burial.
The geo-electric sections enabled to identify the overburden thickness and the depth to the aquifer
along survey lines. Moreover, the vertical electrical sounding survey helped to identify groundwater
potential areas and determine the depth to the aquifer. The study area is probably covered by volcanic
rocks with different degree of weathering and fracturing.
From acidic volcanic rocks Tuff, and pyroclastic deposit are the major unit northeast and southeast
direction from Debre Tabor town. Trachyte plug and flow are outcropped along ribb river
catchment. Whereas from basic volcanic unit, Aphanite basalt, plagioclase basalt, scoracious basalt
and scoria are the main rock exposure in the study area.
Alluvial deposit is outcropped and mapped along ribb river catchment and the banks of other
tributaries.
It is suggested that the apparent resistivity pseudo-depth sections and the true resistivity geoelectric
sections show the presence of shallow as well as deeper low resistivity horizons which are potential
zones of groundwater saturation.
