Geophysical Investigation for Ground Waterpotential Assessment and Mapping Structures at Alidege Plain, South Afar, Ethiopia
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Date
2011-06-06
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Addis Ababa University
Abstract
Vertical Electrical Sounding data collected over the Alidege Plain, located in the Zone 2, of the Afar Regional State has been used in this work. The plain is an extensive flat northeast- southwest running plain in the middle Awash valley with an average width of 26-30Kms and length of more than 70kms. The objective of the VES survey was to make an assessment of the groundwater potential of the plain, with a view to developing the plain both for agricultural and pastoral uses. A total of 90 VES, collected at different field campaigns by the Water Works Design and Supervision Enterprises, has been used. The VES are well distributed over the plain and also a good number of the VES are aligned to enable one to construct a number of sections to depict the subsurface geology of the area. All the VES were individually first interpreted, and to aid in the interpretation of the data, the data were further presented in the form of apparent resistivity pseudodepth sections, sliced-stacked pseudodepth depth sections and true resistivity 2D geoelectric sections. A number of available boreholes distributed over the area were also used to calibrate the VES interpretation. From the combination of these interpretations, it is found that the Alidege plain has adequate groundwater potential with the thick layers of moderately to highly fractured basalts and ignimbrite bearing the good portion of the groundwater resource. A number of structures have also been mapped at varying depths that could control the movement of groundwater and also aid in the location of productive boreholes. From the sliced-stacked pseudodepth sections, it has also been possible to show the direction of regional groundwater movement in the subsurface to be from northeast direction towards southwest direction.
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Geophysical, Investigation, Ground Waterpotential, Assessment, Mapping Structures, Alidege Plain, South Afar, Ethiopia