Browsing by Author "Bunaro, Eyasu"

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    Application of Resistivity Methods for Groundwater Exploration Around Chuko, Southern Region of / Ethiopia
    (Addis Ababa Universty, 1998-06) Bunaro, Eyasu; Haile, Tigistu (PhD)
    Geophysical surveys and studies wereca'riied out in southern Ethiopia around Chuko town for ground water exploration by the hydrogeological team in the Ethiopian Institute of Geological Surveys (BIGS) during 1984 - 1985. These data are reanalyzed from the scientific point of view. It is observed that the apparent resistivity data at a horizon having sufficient thickness can be described by the linear equation where the slope is the same as tangent of the dip angle of the fault. The causes of the principles of equivalence for this particular survey area are aquifers (and possibly aquicludes ) and this problem can be managed by fixing the resistivity value of aquifer known from other information sources such as wells. The results of the inversion shows that the resistivities of all layers associated with aquifers converges towards this fixed value without any change in the depth range indicatinJ the fact that it is not the number of layers but the resistivity value of aquifer that is in the interpretation sounding curves for the ground water exploration. From type curve analysis the assumed faults are investigated which are identical with the ones obtained using profiling results. The type curve mapping is powerful in zone as well as fault mapping. The stacked graphic plot, pseudoelectric and geoelectric section analysis shows that the resistivity of the water bearing fOlll1ations are in general greater than 40 olun-m and these fOlll1ations, which are dominated by fractured volcanic rocks and sands of varying grain size, are most available in the eastern part of the base line with varying depth ranges.
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    Application of Resistivity Methods for Groundwater Exploration Around Chuko, Southern Region of Ethiopia.
    (Addis Ababa University, 1998) Bunaro, Eyasu; Haile, Tigistu (PhD)
    Geophysical surveys and studies were carried out in southern Ethiopia around Chuko town for ground water exploration by the hydrogeological tearn in the Ethiopian Institute of Geological Surveys (EIGS) during 1984 - 1985. These data are reanalyzed from the scientific point of view. It is observed that the apparent resistivity data at a horizon having sufficient thickness can be descnbed by the linear equation where the slope is the same as tangent of the dip angle of the fault. The causes of the principles of equivalence for this particular survey area are aquifers (and possibly aquicludes ) and this problem can be managed by fixing the resistivity value of aquifer known from other information sources such as weDs. The results of the inversion shows that the resistivities of all layers associated with aquifers converges towards this fixed value without any change in the depth range indicating the fact that it is not the number of layers but the resistivity value of aquifer that is in the interpretation sounding curves for the ground water exploration. From type curve analysis the assumed faults are investigated which are identical with the ones obtained using profiling results. The type curve mapping is powerful in zone as weD as fault mapping. The stacked graphic plot, pseudoelectric and geoelectric section analysis shows that the resistivity of the water bearing formations are in general greater than 40 ohm-m and these formations, which are dominated by fractured volcanic rocks and sands of varying grain size, are most available in the eastern part of the base line with varying depth ranges.