A great population growth and rapid industrial development in Taiwan have placed ever increasing demands on the water supply. In fact, since the yield of kno,vn aquifers can no longer meet the current needs, new reservoirs must be found for emergency use, especially in those areas with a short of water. Traditionally, the selection of well sites in Taiwan was based on lineaments shown in aerial photographs and on the topographic conditions of a site. As much as this was successful in the past, the number of potential aquifers today continues to decrease rapidly. Conventional groundwater exploration methods do not give satisfactory results; and locating an aquifer by geoelectric represents a significant challenge. However, the combined geoelectric method and conventional methods provides a better approach for site evaluation, especially in those areas of water shortage.

In this paper, it will be shown the way by which geoelectric methods are applied to locate aquifers in poor water storage areas and highlight the propriety of such methods used during this survey. In so doing, useful information as to the aquifer characterization will be acquired. Two selected sites in this study have different geologic settings; one in a volcanic area, the other in a hilly area. All the geoelectric features obtained in these areas not only delineate the water bearing zones clearly but also indicate the depth extent accurately.