In recent years, electrical resistivity method (ERM) has widely being applied as an alternative tool in engineering, environmental and archeological studies. A global image of groundwater seepage problem was difficult to obtained using conventional geotechnical method due to the efficiency of cost, time and result coverage. This study was conducted using electrical resistivity survey in order to investigate the potential of the problematic zone due to the groundwater seepage problem. ABEM SAS 4000 equipment set was used in during the resistivity data acquisition stage. Six (6) resistivity spread lines (SP) were performed across the slopes area using 2-D electrical resistivity imaging. The raw data was processed using RES2DINV and SURFER software for 2-D and 3-D subsurface image. Interpretation of electrical resistivity results was verified using the existing borehole and geochemistry results. Geochemistry results analyses were used Atomic Absorption Spectrometer (AAS) for determining cation and Ion Chromatography (IC) is for anions. Anion elements were studied consists of chloride, bicarbonate, nitrate and sulfate while cation elements consists of sodium, potassium, calcium and magnesium. All the elements were analyzed by using Piper Diagram to determine geochemistry facies in the groundwater. It was found that low resistivity value (ERV) which associated to groundwater (10 ~ 100 Ωm) can be found starts from the ground surface (0 m) to a greater (> 10 m) depth of the subsurface profile. The finding of the study water seepage can be categorized as Ca-HCO that indicator a typical of shallow fresh groundwater. The finding of the study is important to determine source process of water seepage on that area. This study has successfully demonstrates that the application of ERM with supporting borehole and geochemistry data was able to provide a comprehensive results due to the groundwater leakage detection.
Simulation of Sub-Drains Performance Using Visual MODFLOW for Slope Water Seepage Problem