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Groundwater Potential Assessment Using Integrated Electrical Resistivity and Magnetic Methods : a Case of Ento Catchment, Bodji Dirmejji District,oromia, Ethiopia

Year: 2025
Type: article
Abstract: Major Advisor: Dr. Geremew Lemessa This study was conducted in the Ento watershed region, Bodji Dirmejji district, Oromia, Ethiopia. Water supply has been a problem in the study area. There is now only one existing borehole. The yield of the water is 200 m³ per day (200,000 liters per day), but the population of the town is 22,000 (twenty-two thousand). To close this gap, assess groundwater potential using integrated electrical resistivity and magnetic methods to find out the location of preferred borehole areas and the depth at which the aquifers are located. Data were acquired from fifteen VES points using the Schlumberger electrode array, with a maximum half-current electrode spacing of AB/2 = 330 meters, along with 155 magnetic data points. The VES and magnetic datasets were processed using IP2WIN, IPI2Win-Res3, Surfer 10 (32-bit), and Oasis Montaj 6.4.2 software.The interpretation of VES data was carried out using resistivity curves, geo-electric sections, and pseudosection maps. Similarly, magnetic data interpretation involved several anomaly maps, including total magnetic field, residual magnetic field, analytical signal, and upward continuation maps. Field results from the VES survey revealed zones of low resistivity, suggesting potential groundwater presence. Along Profile 1, VES 3 and VES 4 show a third layer with a thickness of 35 m, resistivity ranging from 76–98 Ωm, and extending to a depth of 51 m. This continues into a fourth layer at VES 4, which is 38 m thick, has a resistivity of 142 Ωm, and reaches a depth of 89 m—indicating favorable aquifer conditions. At VES 8, the third layer is 31 m thick with a resistivity of 61 Ωm and extends to 49 m, while the fourth layer is 38 m thick, has a resistivity of 119 Ωm, and reaches a depth of 87 m—also suggesting aquifer potential. Similarly, the third layer at VES 15, with a thickness of 48 m, resistivity of 62 Ωm, and depth of 62 m, is identified as a promising aquifer zone. Meanwhile, the magnetic survey results revealed low magnetic anomalies in the southwest to northwest regions of the study area, particularly in the upward continuation maps. These low magnetic responses suggest areas of intense weathering and fracturing, likely due to weakened geological structures. The integrated interpretation of VES and magnetic data, along with geological information, provided a comprehensive understanding of the subsurface conditions. Key words: Ento watershed, electrical resistivity, magnetic methods, groundwater, Resistivity Curves, geo-electric section, and residual magnetic field map.
DOI: 10.20372/nadre:14152
Language: English
Subfield: Geophysics
Open Access status: green
OpenAlex ID: W6907201878
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