Application of Geophysical Methods to Delineate Fresh Water Saline and Water Zones in Amibara Irrigation Farm Lands Amibara, Eastern Ethiopia

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Date

2009-06

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Addis Abeba university

Abstract

With the aim to mapping the saline and fresh water interface and verifying the application of geophysical methods to study problems of salinity at the Amibara irrigation farm; electrical methods were applied over two parallel traverses. The methods employed included Schlumberger sounding surveys at ten YES points on the two traverses with YES points spacing of 450 meters to 1100 meters and dipole-dipole surveys over four profiles of approximate length of 250 meters over the same two traverses. The dipole surveys were carried out with three levels expected to give depth of investigations of about 5, 7.5 and to meters. The results of these field surveys are interpreted and presented in the form of geoelctricsections and pseudo sections. A general geological section of the survey area is given from the interpretation of the sounding data. The results have clearly mapped the different geologic horizons of the subsurface and delineated areas of low resistivity due to effects associated with highly saline formation fluids. The work has verified the effectiveness of the electrical methods of prospecting in studying problems associated with salinity and shows the potential of these methods in planning current and near future farm land utilization and monitoring of current pilot desalination programes. Surveys carried out over properly selected sample areas could minimize the cost of obtaining such information from expensive piezometric wells and soil test pits

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Geophysical Methods

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