Very low frequency - electromagnetic (vlf-em) for detecting groundwater river patterns in karst area of kaligambir village

Abstract

Groundwater flow in the limestone areas through gaps, fractures, and dissolving channels whose dimensions and directions are erratic. If the dimensions and direction of the river flow are known, it will be easier to exploit water to meet the needs of the community. The dimensions and direction of the underground river flow can be mapped using the VLF-EM method. VLF-EM measurements were carried out on 18 trajectories spread across two study areas. Each VLF-EM track has a length of 200 meters, taking data at intervals of 2 meters. Processing of VLF-EM data on each path produces a distribution of resistivity values along the measurement path. Resistivity values around Bleri Cave range between 53 Ωm - 685 Ωm, underground river flow is located at a depth of ± 40 meters and the direction of flow is from northeast to southwest. The distribution of underground river flow around the Bleri Cave with resistivity values around the Lowo Cave ranges from 61 Ωm - 550 Ωm, in the area around the Lowo cave there are no underground anomaly caves that are not drained by water. If you want to exploit underground river water it should be done in the area around Bleri Cave.

Mapping Underground River Flows in karst Areas with the VLF-EM Method (Case Study of the Krawak Region, Singgahan Tuban)

“…The previous researchers (Iswahyudi et al, 2023) used the VLF-EM method to search for groundwater river patterns in karst areas. Based on the research results, the direction of the flow pattern and the depth of the groundwater river can be determined from the distribution of resistivity values resulting from VLF-EM data processing [5]. This research uses the VLF-EM method to determine the possibility of subsurface rivers in karst areas in the Montong District.…”