Water seepage erosion has been and remains one of the major engineering problems. However, most engineers will much depend on borehole data and soil test for designing and problem detection. By considering of the cost and destructive method, selection of geoelectrical prospecting would be appropriate. Therefore, two electrical geophysical surveys were carried out in Sekolah Menengah Kebangsaan Dato' Haji Mohd Nor, Gelugor, Pulau Pinang to map the presence of the unknown underground water sources (saturated zones) and its movement. With the total of seven resistivity lines parallel to each other and self potential (SP) with 5 m × 5 m gridding survey were successfully done. The resistivity result from line 1 (R1) to line 6 (R6) shows the subsurface consist of saturated zones with range between 3 m up to 10 m depth, before it reaches the R7 which is believed as the accumulation zone. Meanwhile, as for SP result it shows the water flow from higher value (north-east) towards the lower value which is mostly at the south area. In conclusion, geoelectrical survey could assist in detecting and solving engineering problems as it proven by the result from each method.

Ground penetrating radar (GPR) is a geophysical method that has been developed for shallow subsurface investigation and efficiently used broad area focusing in hydrogeology study. It provides non-destructive and rapid way of obtaining continuous high resolution profiles which are based on the propagation of electromagnetic waves. Conductivity and dielectric properties are two important parameters in GPR method. As in sediment, water saturation primarily causes changes in dielectric properties and therefore, this method is best applied in estimation of depth to water table. Six parallel 2-dimensional GPR lines were executed in Seri Iskandar, Tronoh, Perak, Malaysia with the aim of detecting the depth of water table and analyzing the environment of depositing sediments. Results are presented in 3-dimensional cube for better interpretation and explanation. Based on results obtained, it successfully detected the saturated zone, which suggested as water table with depth of >15-20m. Layer of reclaimed sand detected at depth <3m with nonuniform sand sedimentation and dipping layer detected at depth <10m. Wet zone is detected at depth of <10-15m.

2D resistivity is carried out to detect spread saturated zone and subsurface problems cause by the presence of underground river, which resulted from selected urban area at Selangor, Malaysia. Six 2D resistivity survey lines with minimum 5 m electrode spacing were executed using Pole-dipole array. Borehole was carried out at multiple locations in the study area. Subsequently, the borehole was used to verify the 2D resistivity results. Interpretation of 2D resistivity data showed a low resistivity value (< 40 ohm-m), which appears to be a zone that is fully saturated with sandy silt and this could be an influence factor the increasing water level because sandy silt is highly permeable in nature. The borehole, support the results of 2D resistivity method relating a saturated zone in the survey area. There is a good correlation between the 2D resistivity investigations and the results of borehole records.

ABSTRACT2-D resistivity method is an indirect method to the shallow subsurface survey for maintaining the geo-environment. It is used to measure the apparent resistivity of subsurface. EHR technique was developed in order to get detail and deeper penetration for shallow subsurface study. In this study, 2-D resistivity with Enhancing Horizontal Resolution (EHR) technique is adopted to map and characterize the shallow subsurface (mineral exploration, geology, engineering and environment) using Pole-dipole array. The locations are Pagoh, Johor; Nusajaya, Johor and Puchong, Selangor (Malaysia). The study associated with mineral exploration is Pagoh, Johor while for Nusajaya, Johor is associated with geology and Puchong, Selangor is associated with engineering and environment. The 2-D resistivity and Induced polarization (IP) were employed at Pagoh, Johor to study and detect the subsurface variation of resistivity and chargeability of iron ore in the area. Result of the 2-D resistivity as well as the Induced Polarization (IP) shows that the area is underlain by a thick alluvium with resistivity value of 10 -800 ohm-m iron which has chargeability rate of 0.1 -3 msec. A sedimentary case study was executed at Nusajaya, Johor shows sandstone contains iron mineral (30 -250 ohm-m) and weathered sandstone (500 -1000 ohm-m). Interpretation of 2-D resistivity data at Puchong, Selangor showed a low resistivity value (< 40 ohm-m), which appears to be a zone that is fully saturated with sandy silt and this could be an influence factor the increasing water level because sandy silt is highly permeable in nature. The borehole, support the results of 2-D resistivity method relating a saturated zone in the survey area. There is a good correlation between the 2-D resistivity investigations and the results of borehole records. The stratigraphy and structure of the three case studies (mineral exploration, geology, engineering and environment) can be mapped effectively using 2-D resistivity with EHR technique.