Application of Modified Electrical Resistivity Survey to various Types of Hydraulic Facilities for Leakage Detection

Modified electrical resistivity survey was devised to easily and effectively detect the internal leakage path of hydraulic facilities such as a dam, a reservoir, or a weir. The modified electrical resistivity survey consists of three array: direct potential array, cross potential array, and D-Lux array. The modified electrical resistivity survey has been applied to various hydraulic facilities to be tested for their performance: a concrete weir, a concrete dam, an earth fill dam.

Evidence of leaks was visually found in all three facilities and the surveys were applied to detect the internal leakage path. Depending on the type of facility, the number and location of the survey lines were applied differently, and the source installation way was also applied differently according to the characteristics of the facility. In addition, by using the adhesive electrode in the concrete facility, the damage due to the exploration was prevented.

The modified electrical resistivity survey analyzes the flow and potential fluctuation of the current from the upstream to the downstream across the facility. Therefore, the data analysis focused on identifying the inlet, outlet and path of leakage in the facilities. As a result, the concrete facilities generally leaked along the boundary between the concrete blocks, and the inlet and outlet were confirmed around the boundary. Since the fill dam has much more case of leakage paths than the concrete facility, the leakage path of fill dam was confirmed by the combined analysis of various explorations including the modified electrical resistivity survey. The inlet was close to the drainage pipe installed inside the fill dam, and the outlet was confirmed to be the place where the leakage was presently occurring. In addition, the most convincing internal leakage path was identified through 3D inversion.

The modified electrical resistivity survey is an effective way to detect the internal leakage path of a hydraulic facilities if the survey lines and electrodes installation are considered differently depending on the materials and characteristics of the hydraulic facilities.