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Magnetic Characterization of Sand and Boulder Samples from Citarum River and Their Origin Sudarningsih Sudarningsih; Luki Maulana; Satria Bijaksana; Abd Hafidz; Aditya Pratama; Widodo Widodo; Irwan Iskandar
Journal of Mathematical and Fundamental Sciences Vol. 49 No. 2 (2017)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2017.49.2.2

Abstract

The Citarum River is a nationally strategic river located near Bandung, the capital city of West Java Province. The feasibility of using magnetic methods for monitoring pollution level is currently being tested in the river. Due to its location in a volcanic area, the sediments from the river are expected to be highly magnetic. In this study, sand and boulder samples from Balekambang, a relatively pristine upstream area of the river, were subjected to magnetic and geochemical characterizations to establish the baseline for unpolluted sediments. Such baseline is important for future magnetic monitoring of sediments in the river. The mass-specific magnetic susceptibility of boulder samples was found to be varied from 819.2 to 2340.5 × 10-8m3 kg-1 while that of sand samples varied from 2293.9 to 3845.3 × 10-8m3 kg-1. These high magnetic susceptibility values infer that river sediments are highly magnetic even before being contaminated by industrial and household wastes. The predominant magnetic mineral in sand samples was multi-domain magnetite while that in boulder samples was single to pseudo-single domain magnetite. These differences were supported by the results from petrographic and XRF analyses, implying that the sand and boulder samples originated from different geological formations.
Pemodelan Inversi Data Vertical Electrical Sounding Dengan Menggunakan Algoritma Modified Symbiotic Organism Search (mSOS Mohammad Rheza Zamani; Widodo Widodo
Jurnal Geofisika Vol 20 No 1 (2022): Jurnal Geofisika
Publisher : Himpunan Ahli Geofisika Indonesia (HAGI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36435/jgf.v20i1.533

Abstract

Vertical Electrical Sounding (VES) dengan konfigurasi sclumberger merupakan salah satu teknik dalam metode geolistrik untuk mengetahui model struktur bawah permukaan bumi secara 1D melalui variasi vertikal resistivitas terhadap kedalaman dengan resolusi vertikal yang tinggi. Pemodelan data hasil akuisisi lapangan VES dilakukan menggunakan teknik inversi, inversi data VES merupakan permasalahan non-linier sehingga diperlukan algoritma dengan pendekatan global untuk mendapatkan solusi yang optimum. Pada penelitian ini digunakan algoritma berbasis populasi dengan pendekatan global untuk melakukan pemodelan inversi data VES yaitu modified Symbiotic Organism Search (mSOS) yang terinspirasi dari simbiosis yang terjadi di suatu ekosistem. Algoritma yang digunakan pada penelitian ini terdiri dari 3 tahapan optimasi yaitu mutualisme, komensalisme, dan parasitisme yang masing-masing memiliki peranan dalam peningkatan kapasitas eksplorasi yang berkaitan dengan akurasi solusi dan eksplotasi yang berkaitan dengan kecepatan konvergensi algoritma. Pengujian algoritma mSOS dilakukan pada data sintetik dan data lapangan. Hasil dari pemodelan inversi data sintetik kemudian dibandingkan dengan algoritma damped least-square (DSLQR), Flower Pollination Algorithm (FPA), dan Symbiotic Organism Search (SOS) untuk mengetahui kemampuan eksplorasi dan eksploitasi solusi dibandingkan algoritma lain yang ditinjau dari kesesuaian dari parameter model sintetik dan data sintetik dengan hasil perhitungan, sedangkan pada data lapangan hasil pemodelan inversi dibandingkan dengan perangkat lunak IP2WIN meliputi kesesuaian data observasi dengan data perhitungan inversi dari keduanya dan kesesuaian dengan data lubang bor. Hasil inversi pemodelan data sintetik menunjukan algoritma mSOS memiliki keseimbangan dalam kapasitas eksplorasi dan eksplotasi dibandingkan dengan algoritma lain yang diujikan dibuktikan dengan kemampuan algoritma mSOS yang berhasil mendapatkan kembali model data sintetik dengan tingkat kesesuaian yang paling tinggi dengan waktu konvergensi yang relatif cepat, untuk hasil pemodelan inversi data lapangan juga menghasilkan model yang representatif dengan kondisi bawah permukaan karena bersesuaian dengan data lubang bor serta memiliki tingkat kecocokan data lapangan dan data perhitungan inversi yang lebih baik dari perangkat lunak IP2WIN.
Study of Aquatic Sedimentation Using Electromagnetic Modeling in Flood Hazard Mitigation Scheme Widodo Widodo; M. Rheza Zamani; Sindi Hajah Patimah; Elis Agustiana
Journal of Engineering and Technological Sciences Vol. 55 No. 3 (2023)
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2023.55.3.1

Abstract

The accumulation of sediment in aquatic environments can lead to an increase in flood risk due to raised floodplains and water levels. Electromagnetic modeling techniques, such as Time Domain Electromagnetic (TDEM) resistivity or lithological conductivity contrast, can be utilized to detect changes in the subsurface. In this study, we investigated the use of TDEM in flood hazard mitigation schemes by developing a 1-D forward modeling program for the central loop configuration in an aquatic environment using the Adaptive Born Forward Mapping (ABFM) method. The program was tested in various environmental conditions, i.e., freshwater, brackish water, and saltwater, to determine its response. The objective is to prevent natural disasters, particularly flooding caused by sedimentation. The TDEM models can generate images of sediment thickness, providing a sensitive response in saltwater environments and enabling the detection of changes in depth compared to other aquatic environments. Overall, this study demonstrated the potential of TDEM as a valuable tool in flood hazard mitigation schemes.
Quasi-3D Geoelectrical Imaging as A New Application for Landslide Investigations: A Tunnel Case Induced by Blasting Activity Cahyadi, Rudi; Widodo, Widodo
Jurnal Ilmu Fisika Vol 16 No 2 (2024): September 2024
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.16.2.177-186.2024

Abstract

Landslides are a significant hazard in mountainous regions, especially when influenced by construction activities such as tunnel excavation. In this paper, we aim to conduct a slope stability analysis as a result of tunnel blasts using quasi-3D subsurface models based on resistivity values. The study site is a construction area for the Jakarta-Bandung High-Speed Train tunnel, located in a mountainous region undergoing drill-and-blast excavation. This excavation method makes the area susceptible to landslides, which pose a threat to settlements in the Padalarang subdistrict, West Bandung Regency, Indonesia. Data was collected along four lines in 2D, and the dipole-dipole array was used to enhance resolution. Data modeling was carried out using ResIPy v3.2.3 software to create 2D and quasi-3D subsurface models based on resistivity values. The study findings indicate that the study area exhibits three resistivity ranges: low resistivity (0-30 Ωm), medium resistivity (31-49 Ωm), and high resistivity (>50 Ωm). Utilizing quasi-3D imaging, we were able to identify the dimensions and presence of slip surfaces, which can be categorized as shallow (1.5-5 m) and deep (5-20 m) criteria. This study successfully applied the quasi-3D geoelectrical approach in a susceptible environment to detect potential landslide zones.
Studi Komparatif Triangular dan Quadrilateral Mesh pada Inversi Geolistrik 2D Wenner-Schlumberger untuk Zona High resistivity di Terowongan 11 Padalarang Rudi Cahyadi; Widodo Widodo
Jurnal Fisika Unand Vol 14 No 6 (2025)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.14.6.546-553.2025

Abstract

This study aims to compare the results of 2D electrical resistivity inversion using triangular and quadrilateral mesh types in the Wenner–Schlumberger configuration to identify high-resistivity zones at Tunnel 11, Padalarang. Data acquisition was performed using 48 electrodes with a 10 m spacing and an ARES II multichannel resistivity meter. Data inversion was conducted with the ResIPy software employing two different mesh approaches. The results show that the triangular mesh produces smoother models, better adapts to topography, and achieves lower root mean square (RMS) errors (1.09–1.12%) compared to the quadrilateral mesh (4.67–4.72%). High-resistivity zones (>60 Ωm), interpreted as andesitic basalt, were identified at depths greater than 25 meters. The extent of these zones increases from Line 2 to Line 1, which has implications for blasting or drilling strategies during tunnel construction. These findings indicate that triangular mesh is more effective for complex geological conditions.
Pengembangan Sistem Penyediaan Air Bersih Pedesaan di Desa Wai U, Kecamatan Mangoli Tengah, Kabupaten Kepulauan Sula, Provinsi Maluku Utara Arno Adi Kuntoro; Resanti Audrienne; Rofidzias Siswo Wicaksono; Almira Abdul Kholik; Vicky Candra Purnama; Fahrul Kedafota; Widodo Widodo; Salsa Alfadhila Permana; Mohammad Farid; M. Bagus Adityawan; Widyaningtias Widyaningtias; Ana Nurganah Chaidar
Agrokreatif: Jurnal Ilmiah Pengabdian kepada Masyarakat Vol. 11 No. 1 (2025): Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat
Publisher : Institut Pertanian Bogor

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29244/agrokreatif.11.1.133-144

Abstract

Wai U Village has a problem with the limited capacity of the village's clean water supply system. This community service activity aims to retrofit the existing clean water supply system, which previously experienced technical problems, and to increase the capacity of the existing system. The implementation method consists of pre-site visit interviews, field surveys, geoelectric surveys to determine aquifer potential, and water quality laboratory tests for drinking water standards. The results of the geoelectric data analysis show that the potential aquifer was located at 30m below the surface. The water quality test results show that the groundwater quality generally meets the class-1 water quality standards for drinking water. Field survey activities were followed by the construction of groundwater wells, water towers, water reservoirs, pumps, and a series of pipes connecting the new water sources to the existing pipe distribution network of Wai U Village. The final result of this activity was the improvement of the clean water supply capacity in Wai U Village, which was able to connect houses that previously depended on water sources from dug wells. There are 69 houses in the Wai U Village. Before experiencing technical problems, the existing water supply system (Pamsimas) in Wai U Village was connected to 38 houses (55%). The construction of new water supply infrastructure was connected to the remaining 31 houses (45%); thus, this activity has succeeded in increasing clean water network connections by almost 100% in Wai U Village. However, several house connections require rehabilitation. This activity is expected to be one of the real contributions of universities to achieving water, food, and energy security in Wai U Village, which is categorized as a 3T region.
Scanning Electron Microscopy and Magnetic Characterization of Iron Oxides in Suspended Sediments Sudarningsih Sudarningsih; Satria Bijaksana; Widodo Widodo; Irwan Iskandar; Darharta Dahrin; Silvia Jannatul Fajar; Kartika Hajar Kirana; Raghel Yunginger
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 14, No 2 (2024): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v14i2.76582

Abstract

River sediment is the product of a sedimentation process in the river environment that originates from the weathering of bedrock or erosion processes, organic materials, particles, or anthropogenic substances. Previous research shows the magnetic mineral content in the sediments of the Citarum River and its tributaries. Suspended sediment was collected from the Citarum River and its tributaries in West Java, Indonesia, for mineralogical and granulometric analysis. The aim of this research is to distinguish between magnetic mineral sources, a scanning electron microscope equipped with energy dispersive X-ray spectroscopy (SEM-EDX), and rock magnetism. The hysteresis parameter verifies that the XRD measurement results show that the main magnetic minerals in suspended sediments are ferrimagnetic minerals such as magnetite (Fe3O4). According to the results of the SEM-EDX investigations, the magnetic granules in the Citarum River and its tributaries derive from two distinct sources: pedogenic and anthropogenic. The Citarum River and its tributaries’ magnetic granules are generally octahedral or angular in shape, with broken corners, indicating a pedogenic origin