The electromagnetic (EM) geophysical method has been used widely in many areas for groundwater prospecting but interpretation of data for accurate location of water bearing features is still a problem. A simple method of data interpretation has been developed and applied in the sedimentary formation of the Voltaian basin of Ghana for groundwater exploration. The interpretation scheme is based on identifying EM highs along parallel traverses of EM profiling data that are presented on one-dimensional (1-D) plots. The results show terrain conductivity distribution in the range of 10-70mS/m for the vertical dipole (VD) mode of the device and 22-79 mS/m for the horizontal dipole (HD) mode pertaining to the general conductivity distribution of the area, using a 20m inter coil separation cable. The conductivities for the HD mode were generally higher than those for the VD mode. The plots show various patterns of EM signature as indications of possible water bearing features. On the basis of defined criteria, the best ranking drill targets were selected for boreholes. The interpretation of EM results helps to delineate water bearing features for a high success drilling rate. The signatures can easily be visualized from the plots facilitating data interpretation. Higher conductivity values for the HD modes suggest the existence of a subsurface clay layer.
|Number of pages||16|
|Journal||Journal of Environmental Hydrology|
|Publication status||Published - Jan 1 2009|
ASJC Scopus subject areas
- Water Science and Technology