Groundwater Level Detection by Using a Two-Dimensional Electrical Resistivity Imaging

Abstract

Groundwater level is one of the main factors that should be considered in slope stability analysis. Generally, surface water resulted from rain infiltrates to the ground will increase the groundwater table, thus can trigger slope failures. Many methods can be employed to explore and investigate the presence of water in the sloping areas. One of the conventional methods that are commonly used is observation well where piezometer is installed in the well. The purpose is to measure the level and hydraulic head of groundwater in aquifers. However, this kind of technique needs to be dealt with tedious works as drilling is to be carried out for standpipe installation. Even though this technique is technically easy to understand, it only can provide one single point water level data of the area unless there are a numbers of well to be drilled. This means that the observation well can only provide the information at a discrete point. In order to obtain continuous ground water level and other underground profile a technique that can provide the continuous sub-surface information should be carried out. This paper presents findings of a study of groundwater detection using a non-destructive method namely electrical resistivity imaging. The objective of the study is to determine how reliable the method can be used in detecting ground water level and to what extent it can provide the sub-surface information. A 2-D electrical resistivity imaging was carried out on two slope areas where a landslide was taken place at one of the areas. The groundwater level was also monitored using the observation well at very limited borehole points. The results of the 2-D electrical resistivity imaging and piezometer then were compared.