THE COMBINED VES/EM SOUNDINGS GEOPHYSICAL METHOD FOR SITING BOREHOLES

Abstract

A new simple and quick geophysical method for the siting of boreholes for groundwater supply has been developed from sediments of Aber College Farm, Gwynedd, North Wales, U.K. Vertical Electric Soundings (VES) are made to locate a potential sub-surface feature which is then assessed by making Electromagnetic (EM) soundings at the selected center of the site where previously VES is made. Groundwater quality has a significant influence on the data. The method and criteria for selecting a site are described in detail. Careful site selection is important in reducing the time and money spent on unproductive drilling. In the sediments. 5 boreholes had good rates of groundwater production out of 7 sites selected using this method.