Mapping Hydrogeological Structures Using Transient Electromagnetic Method: A Case Study of the Choushui River Alluvial Fan in Yunlin, Taiwan

We used transient electromagnetic (TEM) to map the hydrogeological structures in Choushui River Alluvial Fan Yunlin County of central Taiwan. A total 63 TEM measurements were collected using FASTSNAP system with 50 × m in-loop configurations middle and distal fan. The 1D model, based on prior information, was constructed from inverted soundings. Results showed a thin, resistive shallow layer 40 low-resistive (6–42 ohm-m) zone beneath it. High-resistive zones (50–170 found 50–120 depth, revealed below 120 some areas. consistent resistivity lithology logs nearby wells. models provide reliable subsurface information when informations vertical electrical sounding considered. interpolated at 10 m, 100 160 depth model results produce slice area, which indicated variations, trends, depths sediment deposits. method successfully identified structures, showing that upper acts as confining for aquifer structure depth.