Assessment of aquifer susceptibility to land subsidence due to groundwater over-exploitation in Yogyakarta-Sleman groundwater basin

Abstract

Land subsidence due to groundwater over-exploitation has already become a problem in many countries and also some cities in Indonesia. Although there have been many studies that explain the occurrence of land subsidence in various places, there is still limited research that discusses prediction techniques or mapping the potential of land subsidence in an area. This research aims to determine the susceptibility zone of land subsidence due to groundwater over-exploitation in Yogyakarta-Sleman Groundwater Basin. In this study, the land subsidence susceptibility will be determined based on three parameters namely aquifer stratification, a combination of aquitard and aquiclude layers thickness, and compressibility potential of aquitard and aquiclude layers. The data used in this research is secondary data of 126 drill logs along with their descriptions which are then processed to generate litho-stratigraphy modeling and are also processed using Geographic Information System (GIS) software for the interpolation and extrapolation also to generate zoning maps of each parameter. After that, all three parameters were overlayed by applying Analytic Hierarchy Process (AHP) weighting method to produce a susceptibility map of land subsidence due to groundwater over-exploitation. A prediction of land subsidence hazard map is also created by overlaying the susceptibility with relatively groundwater pumping rate zones. The research reveals the central part of the basin belonged to a severely susceptible and hazardous zone. According to this research, it can be concluded that there is a potential for land subsidence due to groundwater over-exploitation in the Yogyakarta-Sleman groundwater basin area, so the management to control of the groundwater usage is needed to ensure sustainable use of groundwater and protection from land subsidence occurrence.