Investigating Land Use and Karst Disaster Mitigation through Geoelectric and Magnetotelluric Methods: A Case Study in Sendang Biru, Malang, Indonesia

Abstract

Sendang Biru Beach, located in Sumbermanjing Wetan District, South Malang Regency, East Java Province, Indonesia, offers significant tourism and fisheries potential, supported by the nearby Sempu Island Nature Reserve and a Fish Auction Site (FAS). However, the coastal region is prone to karstification, which may be exacerbated by recent land use developments in the surrounding area. This study aims to analyze the rock layer structures and assess the vulnerability of karst land use to the ongoing karstification process. Electrical Resistivity Tomography (ERT) and Magnetotelluric (MT) methods were employed to investigate karst land within the study area. The findings revealed the presence of karst aquifers in Zone A, extending to a depth of 250 m, characterized by low resistivity values. In Zone B, karst limestone deformation was observed at several locations due to karstification, with moderate resistivity values detected at a depth of 300 m on the surface, indicating vulnerability to karst disasters. High resistivity values dominated areas with massive karst limestone, ranging from the surface to a depth of 400 m. Furthermore, it was found that a significant portion of karst land is utilized for settlements, plantations, and rice paddies, potentially disrupting the karst ecosystem due to household, plantation, and agricultural waste. This study highlights the importance of understanding the impact of land use on karst vulnerability and informs mitigation strategies for sustainable development in the Sendang Biru region.