Browsing by Author "Merga, Dereje"

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    Geophysical Investigations for Groundwater Potential Assessment of Volcanic Plain, Mermero Area, Borena Zone
    (Addis Ababa University, 2015-06-06) Merga, Dereje; Haile, Tigistu (Professor)
    Geophysical investigation methods of Vertical Electrical Sounding and magnetic prospecting were used to investigate groundwater potential zones of Mermero area, Borena zone, Southern Ethiopia. The main objective of this study is to determine the depth of groundwater table, to locate the groundwater potential areas and to identify the subsurface layers. The data acquired from twenty eight (28) Vertical Electrical Sounding points and 663 magnetic data points, which were interpreted both qualitatively and quantitatively in order to understand the lithostratigraphic section at the specific locality and identify aquifer bearing horizons. The qualitative analysis of Vertical Electrical Sounding data were performed by using pseudo depth sections and geo-electric section and different apparent resistivity maps. Similarly, the qualitative interpretations of magnetic data were performed by total magnetic variation plot and different magnetic anomaly maps. Finally, the qualitative interpretation was done by all the above results together with the geologic, topographic maps and borehole information. From the analysis result, geologic structures and groundwater potential zones are identified. The quantitative interpretations of the Vertical Electrical Sounding data were conducted by modeling the sounding data using Ip2win and Win Resist modeling software and constructing geoelectric sections along selected survey lines, using the result from individual Vertical Electrical Sounding point interpretations. The depth and lithologic units from the boreholes were used to fix parameters during the modeling of Vertical Electrical Sounding data. The geoelectric sections enabled to identify the overburden thickness and the depth to the aquifer along survey lines whereas the magnetic method complemented the finding of the other geophysical methods regarding structural indication such as faults, fractures and lithologic contacts.