IDENTIFICATION AND MAPPING OF GROUND WATER POTENTIAL USING GEOELECTRICAL RESISTIVITY SOUNDING (VES) AND GEOSPATIAL TECHNOLOGY METHODS IN CASE OF ROBBI CATCHMENT, AMHARA, ETHIOPIA MSc

Advisor: Dr. Fekadu Tamru (PhD)

Groundwater is a vital resource for addressing water scarcity. This study employs a combination of Vertical Electrical Sounding (VES) and Geospatial Technology to identify groundwater potential sites in the Robbi River catchment, North Shewa, Amhara, Ethiopia. The VES method based on resistivity measurements was utilized to explore the subsurface lithology, aquifer depth, and groundwater-bearing formations. A total of 20 VES points were thoughtfully distributed across the study area, and the resistivity data were analyzed using software tools (IPI2WIN) to construct 1D geoelectrical models. These models revealed key hydrogeological parameters, including aquifer thickness and resistivity variations, which were crucial for groundwater assessment. Geospatial technology, complemented the VES results by integrating spatial datasets such as geology, land use/land cover, soil type, rainfall and drainage patterns. The analysis of these datasets categorized the study area into high, moderate, low, and very low groundwater potential zones. The study's integration of VES and geospatial tools identified high potential groundwater zones in the Robbi River catchment, offering a scientific basis for sustainable management and water supply solutions. Generally, the study area exhibits complex resistivity and two aquifer types: shallow and deep. The deep aquifer, found near profiles one and profile two at 300m depth, is slightly fractured basalt confined by alluvium (6-18Ωm) above and massive bedrock (134Ωm) at the bottom. The shallower aquifer along profile three and four (less than 100m deep) consists of highly fractured and slightly weathered basalt, underlain by bedrock with a resistivity of 100Ωm. In conclusion, Based on geological (GIS) and geophysical (VES) investigations The area exhibits high groundwater potential, particularly in slightly fractured and weathered basalt as well as thick alluvial deposits with coarse-grained sediment formations serve as productive aquifers capable of significant groundwater storage and flow. The deeper aquifer, potentially a more reliable resource due to its protection by bedrock. It is significantly deeper than the more vulnerable shallow aquifer to allocate boreholes. Overall, the combination of fractured volcanic rocks and thick alluvial layers are the suitable site in the Robbi River catchment for borehole allocation, Especially near profile one and beneath profile two.
Keywords : Pseudo and Geo-electric section; VES, , GIS, and electrical method.