A large data set of more than 330 transient electromagnetic (TEM) soundings was collected in the southwest coast of Taiwan, The aims of the study were (1) to define the shallow geoelectrical structure, and (2) locate large bodies of ground water by integrating electrical anomalies and data from more than 140 wells, A one-dimensional, smooth-model inversion of TEM data was used, and trend surface analysis of those results was employed to refine the results for interpretation, A resistive zone (15 to 160 ohm-m resistivity) at elevations 20 to 120 m below sea level in the northern part of the survey area is interpreted as fresh water saturated sand or gravel, The southern part has extremely low resistivity, less than 1 ohm-m, indicating a widespread sea water intrusion. The divide between these two parts is located at about the middle of the study area. This study demonstrates that TEM investigation can help resolve ambiguities, even in an area with many wells, and thereby increase the likelihood of success in ground water exploration.
