Application of Resistivity And Magnetic Method for Characterizing Type and Depth of Aquifers Favorable for Groundwater Potential Along Shashimene-Kofele Road, Central Main Ethiopian Rift.
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Date
2018-06-02
Authors
Degife, Tariku
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Publisher
Addis Ababa University
Abstract
In this study resistivity and magnetic methods are applied for characterizing type and depth of aquifers favorable for groundwater potential along Shashimene-Kofele road, in central Main Ethiopian Rift. The fast growing population, and expansion of industrial activities in the study area demanded to assess groundwater potential and aquifer character. This study is aimed at assessing hydrogeological conditions of the area with the view of delineating subsurface layers and structures. Geophysical methods employed in this study are, Vertical electrical sounding and magnetic survey technique. Electrical sounding was used to investigate and ensure the potentiality of the groundwater. On the other hand, magnetic survey was used to delineate geological structures which control the groundwater flow system.
The geophysical survey comprises, twenty VES readings by using Schlumberger array along five survey lines, and above two hundred magnetic reading at about 30meter interval along two profiles. The field data obtained was processed and analyzed by using special computer soft wares. Information from nearby boreholes were incorporated to constrain resistivity and 2D model with geological layers and to enhance the result. The results of the geophysical survey are presented in the form of interpreted VES curves, sliced stacked map, pseudo depth section, geoelectric section, magnetic anomaly plot and 2D model.
The study result revealed four to five main geoelectric layers that differ in degree of weathering and fracturing. The highly weathered and fractured ignimbrite with sandy soil is the main water bearing horizon which has good groundwater potential. The aquifer thickness in the area is obtained to range between 50m and 160m. The result also revealed, the area is transected by several subsurface geological structures that are important for the movement and occurrence of groundwater. From the overall results, eight well sites are recommended for drilling based on their priority order. Detail geophysical survey and geochemical analysis are recommended along the proposed sites for farther studies.
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Keywords
Aquifer, Groundwater Potential, Ves, Geoelectric Section, Highly Weathered and Fractured Ignimbrite