Application of Very Low Frequency (VLF) Method for Underground River Estimation in Donorojo Sub-District, Pacitan

Ayi Syaeful Bahri, Khusnul Nur Rochmah, M. Haris Miftakhul Fajar, Juan Pandu Gya Nur Rochman, Wien Lestari, Fachri Almawali Abil Fida

Abstract

Pacitan is included in the Gunung Sewu karst area in the Southern Mountain Zone, and carbonate rocks dominate the constituent rocks. Karst has a unique drainage system because it is dominated by subsurface flow. This research was conducted in Cemeng and Klepu villages, Donorojo sub-district, Pacitan, with 4 track data. Data were collected using the very low frequency electromagnetic (VLF-EM) method with a track length ranging from 200-450 m, a measurement spacing of 5 m, and a transmitter frequency of 19.8 kHz. Data processing uses filtering and inversion, resulting in a cross-section of resistivity values. Based on the subsurface resistivity cross-section profile, the cavity in the carbonate rock layer with a resistivity value of 0-500 Ωm is identified as an underground river. The underground river is found on tracks 1, 2, 3, and 4 near the surface, with a depth of about 30 m below the surface.

Keywords

Resistivity; Underground River; VLF-EM

Full Text:

PDF

References

I. A. kusuma Wardani and S. U. Nafiah, “Analisis Spasial Potensi Tingkat Kekeringan di Kabupaten Pacitan,” J. Geogr., vol. 20, no. 1, pp. 1–8, Aug. 2022, doi: 10.26740/jggp.v20n1.p1-8. 2 J. D. McNeill, “Use of Electromagnetic Methods for Groundwater Studies,” in Geotechnical and Environmental Geophysics, no. 2, Society of Exploration Geophysicists, 1990, pp. 191–218. 3 A. Kuswanto, “Aplikasi Metoda Res-2D Untuk Eksplorasi Air Bawah Tanah Di Daerah Kars,” J. Air Indones., vol. 1, no. 2, pp. 226–234, 2005, doi: 10.29122/jai.v1i2.2349. 4 F. P. Bosch and I. Müller, “Improved karst exploration by VLF‐EM‐gradient survey: comparison with other geophysical methods,” Near Surf. Geophys., vol. 3, no. 4, pp. 299–310, Nov. 2005, doi: 10.3997/1873-0604.2005025. 5 R. W. Van Bemmelen, “The Geology of Indonesia. General Geology of Indonesia and Adjacent Archipelagoes,” Government Printing Office, The Hague. pp. 1–766, 1949. 6 M. Karous and S. E. Hjelt, “Linear Filtering of Vlf Dip‐Angle Measurements,” Geophys. Prospect., vol. 31, no. 5, pp. 782–794, 1983, doi: 10.1111/j.1365-2478.1983.tb01085.x. 7 M. Padlilah et al., “Identifikasi Sungai Bawah Permukaan pada Data Resistivitas 2d Konfigurasi Dipole-Dipole di Desa Gedompol, Kabupaten Pacitan,” J. Geosaintek, vol. 7, no. 3, pp. 125–134, Dec. 2021, doi: 10.12962/j25023659.v7i3.10950. 8 Fraser, “Contouring of Vlf-Em Data,” Geophysics, vol. 34, no. 6, pp. 958–967, 1969, doi: 10.1190/1.1440065. 9 M. A. Khalil and F. M. Santos, “Comparative Study Between Filtering and Inversion of VLF-EM Profile Data,” Arab. J. Geosci., vol. 4, no. 1–2, pp. 309–317, Feb. 2011, doi: 10.1007/s12517-010-0168-4. 10 F. A. Monteiro Santos, A. Mateus, J. Figueiras, and M. A. Gonçalves, “Mapping groundwater contamination around a landfill facility using the VLF-EM method — A case study,” J. Appl. Geophys., vol. 60, no. 2, pp. 115–125, Oct. 2006, doi: 10.1016/j.jappgeo.2006.01.002. 11 F. A. M. Santos, “Instructions for Running PrepVLF and Inv2DVLF 2-D Inversion of VLF-EM Single Frequency Programs,” Portugal, 2006. 12 Sungkono, B. J. Santosa, A. S. Bahri, F. M. Santos, and A. Iswahyudi, “Application of Noise-Assisted Multivariate Empirical Mode Decomposition in VLF-EM Data to Identify Underground River,” Adv. Data Sci. Adapt. Anal., vol. 8, no. 3, pp. 1–23, 2016, doi: 10.1142/S2424922X1650011X.

DOI: https://doi.org/10.13057/ijap.v14i2.83171

Refbacks

  • There are currently no refbacks.