Application of electrical resistivity to assess subsurface geological and hydrological conditions at post‐tin mining sites in Indonesia

Abstract

In many parts of Southeast Asia, opencast hydraulic tin mining has been carried out since the colonial era. Regardless of its scale, this mining method has significantly affected microtopography and left extremely degraded soil surfaces, where vegetation can hardly grow. Therefore, the identification of a feasible method for the rehabilitation and reforesting of these areas is a long‐term issue. In this study, we aimed to clarify the subsurface geological (soil properties and distribution) and hydrological conditions at a post‐tin mining site on an Indonesian island using an electrical resistivity survey combined with microtopographic information. The electrical resistivity survey of the study site provided information about the distribution of bedrock and sandy and clayey soils, reflecting mining activities. Furthermore, direct and continuous groundwater level monitoring showed the ranges of groundwater fluctuation depending on the soil and climate conditions. Our study demonstrates that subsurface assessment by electrical resistivity survey can provide essential information, contributing to the development of feasible plans for reforestation or transformation to agricultural land at post‐tin mining sites through the improvement of physical conditions and soil fertility.