Groundwater Potential Assessment Using Geoelectrical Data: A Case Study Of Phuket Island, Thailand

Abstract

Groundwater is the dominant source of water supply on Phuket island, Thailand. The water demand on Phuket has been increasing due to rapid urbanization and population growth. A scarcity of freshwater and over-extraction of groundwater may shortly become severe problems for Phuket. Geoelectrical data obtained by Vertical Electric Sounding (VES) were employed in this study to estimate the Dar Zarrouk parameters of the study area. Twenty-four VES stations were set up using Schlumberger configuration with a 1.0 m minimum spacing. The lithology layers from 24 unpublished borehole data indicating each subsurface layer were validated with the resistivity data obtained from VES. The geoelectric profiles gave a maximum of three layers with varying resistivities and thicknesses across each VES station. Two parameters (longitudinal conductance and transverse resistance) of the Dar Zarrouk model were calculated from VES data to generate the thematic maps in a GIS environment, thus the groundwater potential in Phuket Island was represented as a single map by using the weighted overlay technique in ArcGIS, based on both longitudinal conductance and transverse resistance. The groundwater potentials were classified into three potential levels (low, medium, and high). The results reveal that the highest groundwater potential areas are isolated and in specific locations, while the majority of area has medium level groundwater potential. Finally, the low potential zones are in the flank and the top parts of the study area.