Jurnal Geosains dan Remote Sensing (JGRS)
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Multidirectional Lineament Analysis from DEMNAS Digital Elevation Model, Application for Detection Permeability Zone Tulehu Geothermal Field, Central Moluccas
Get PDFThe morphological lineament on the surface detected by satellite imagery expresses the geological structure in the form of faults, fractures, joints, and other geological structures. Identification of geological lineaments is useful for analyzing tectonic history, exploring geological resources, and mitigating geological disasters. Exploration of geological resources, one of which is geothermal, continues to be developed to meet the world's growing energy needs. Therefore, the main objective of this study is to extract lineaments using the multidirectional irradiation method from DEMNAS images applied to analyze the permeable zone in the Tulehu geothermal field, Central Moluccas. To optimally identify the geological lineament, lineament extraction is carried out using the multidirectional irradiation method from DEMNAS imagery which has a spatial resolution of 0.27 arcs, which is then quantified lineament density in a grid with an area of 1x1 km2. The quantification result of the highest lineament density is 3.47 km/km2. The permeability zone at the study site is at a lineament density value greater than 1.6 km/km2, which is associated with sedimentary rocks and lithological boundaries. Overall, the multidirectional method of DEMNAS images produces detailed visual images so that lineament extraction can be carried out optimally
Pemanfaatan Penginderaan Jauh Untuk Pemetaan Alih Fungsi Lahan Sawah di Kabupaten Nganjuk
Get PDFTeknologi Penginderaan Jauh dapat dimanfaatkan untuk melakukan monitoring terhadap alih fungsi lahan sawah. tujuan dari penelitian ini adalah guna untuk melakukan analisis konversi lahan sawah di Kabupaten Nganjuk dengan memetakan konversi lahan sawah di wilayah tersebut. Penelitian berlokasi di Kabupaten Nganjuk, Jawa Timur. Pemrosesan dalam penelitian ini menggunakan Google Earth Engine dan ArcMap 10.8. Dalam penelitian ini data yang digunakan adalah citra Sentinel-2A dan shapefile Kabupaten Nganjuk. Penelitian menunjukkan hasil bahwa terjadi penurunan luas lahan sawah di Kabupaten Nganjuk selama 2016-2022 mencapai 14.500 ha. Namun lahan terbangun mengalami kenaikan sebesar 5.900 ha. Berdasarkan hasil uji akurasi pada tahun 2016 memiliki hasil uji overall accuracy dan kappa accuracy sebesar 0,9526, tahun 2019 nilai hasil uji akurasi overall accuracy dan kappa accuracy sebesar 0,9459 dan untuk tahun 2022 memiliki nilai hasil uji akurasi keseluruhan dan uji kappa accuracy sebesar 0,9027 Hasil penelitian ini menunjukkan terjadinya perubahan fungsi lahan sawah di Kabupaten Nganjuk, kondisi ini dapat memberikan pengaruh terhadap kinerja sektor pertanian dan berakibat pada ketersediaan pangan lokal maupun nasional
Rapid Flood Inundation Mapping Using Multi-Temporal Sentinel-1 SAR: An Example from Kendari City
Get PDFInformation regarding flood inundation presented through maps provides valuable information in preparedness and flood mitigation efforts when a disaster occurs by utilizing the potential of satellite imagery. This study aims to map flood inundation areas by integrating Sentinel-1 Synthetic Aperture Radar (SAR) data and the Otsu method. The results were validated with a confusion matrix and compared water areas that were flooded (March 2022), not flooded (February 2022), and flood seasons in previous years (April 2017 and June 2018). Historical patterns of rainfall are also analyzed to understand flood events. The overall accuracy and Kappa coefficient of the 22 March 2022 flood inundation map are 95.81% and 0.86, respectively. Areas that are submerged (region under water) classify floods well compared to areas that are not flooded (February 2022). Classification results in April 2017 and June 2018 also show the same thing. Sentinel-1 SAR which is integrated with the Otsu method in GEE can map flood inundation areas quickly and in Near-real time and increase the existing possibilities to save the grassroots and community's economic resources and protect infrastructure
Stratigraphic Analysis and Depositional History of Kubang Area, Cianjur Regency, West Java
Get PDFKubang area, Cianjur Regency, West Java, is composed of well-preserved sedimentary rock formations, especially along the Cibeet River, which borders Bogor and Cianjur. This study aims to identify, reconstruct, and make models of the geological history in the research area from a stratigraphic perspective. The method used in this research consists of field observation, fossil analysis, and measuring sections, and making geological model. The data were analyzed, combined, interpreted, and simulated to become a depositional history model. Based on the results of the stratigraphic strata in the research location, the order of formations from oldest to youngest is Jatiluhur Formation of Marl and Quartz Sandstone Member (Mdm), Cantayan Formation of Breccia Member (Mttb), Cantayan Formation of Claystone Member (Mttc), Cantayan Formation of Sandstones Member (Mtts), Mangerit Intrusion (Ma), Limo Volcanic Deposits (Qyk), and Alluvial Deposits (Qa). The sedimentation process began in the Early Miocene and continues to the present. Past depositional processes in the Neritic environment were dominated by transgression-regression accompanied by volcanism played an important role, so unique and repetitive lithological units formed. This research contributes to understanding the history of deposition in the Kubang area and provides information for future research
Geological Perspective as Karst Geotourism Potential: A Case Study of Vientiane Province, Laos
Get PDFThe Vientiane Province is located in the northern region of Laos and is primarily characterized by a karst environment. This area holds significant potential for geotourism, much of which remains largely unexplored. The blend of natural and cultural attractions makes this region appealing for visitors. Situated in the subduction zone between the Sibumasu and Indochina plates, this area gave rise to the Loei-Phetchabun volcanic belt during the Late Permian to Early Triassic periods. The interaction of these tectonic plates has resulted in a diverse array of rock types, minerals, and unique landforms. Such geological diversity is found in only a few places worldwide, emphasizing the need for conservation efforts, including the designation of this region as a geosite for ecotourism. The aim of this research is to examine the potential of karst landscapes for geotourism. Three selected geosites in the region Muang Met, Kasy, and Vang Vieng districts each have distinct characteristics that highlight different geological features, including karst environments, fault zones, spectacular rock outcrops, fossils, caves, temples, rivers, and cultural centers. We have developed guidelines for geotourism development in this area. As this geotourism study is preliminary, it is currently limited to a few locations, with other potential geotourism sites yet to be explored. To facilitate visitor access, we have created a travel route map and designated stop sites. An overview of each district, including potential challenges to geosite development, is provided in the discussion. Sustainable geotourism development in Vientiane Province is expected to have a positive impact on the local community's social and economic well-being. We hope this paper opens up new opportunities for ecotourism in Laos, potentially paving the way for the region to be recognized as a national geopark
Identifikasi Jenis Fluida Pada Zona Target Hidrokarbon Berdasarkan Nilai Saturasi Air (Sw) di Lapangan Migas “BGS” Cekungan Jawa Timur Utara
Get PDFCekungan Jawa Timur Utara adalah back arc basin yang terkenal dengan kekayaan sumber daya hidrokarbonnya, menjadi fokus utama industri migas di Indonesia. Pada cekungan ini terdapat lapangan migas yang memiliki potensi signifikan dalam hal produksi minyak dan gas bumi. Untuk mengoptimalkan potensi ini, maka perlu pemahaman yang mendalam terkait jenis fluida yang ada pada reservoar. Salah satu parameter fisik yang penting dalam mengidentifikasi jenis fluida di dalam reservoar adalah nilai saturasi air (Sw). Tujuan penelitian ini adalah mengidentifikasi jenis fluida berdasarkan nilai saturasi air pada 7 (tujuh) sumur yaitu BGS1, BGS2, BGS3, BGS4, BGS5, BGS6, dan BGS7. Penelitian ini menggunakan metode Well Logging dengan data log yang digunakan yaitu log gamma ray, log resistivitas, log porositas, dan log densitas. Berdasarkan hasil penelitian, pada Sumur BGS1 terdapat 5 zona dengan fluida minyak dan gas, sumur BGS2 terdapat 2 zona dengan fluida minyak dan gas, sumur BGS3 terdapat 2 zona dengan fluida minyak dan gas, sumur BGS4 terdapat 2 zona dengan fluida minyak, sumur BGS5 terdapat 1 zona dengan fluida minyak, sumur BGS6 terdapat 3 zona dengan fluida minyak dan gas, dan sumur BGS7 terdapat 1 zona dengan fluida minyak. Berdasarkan hasil analisis lapisan reservoar pada sumur BGS1, BGS2, BGS3, BGS4, BGS5, BGS6 dan BGS7 Cekungan Jawa Timur Utara secara umum didapatkan nilai saturasi air sebesar 20% - 70% dengan fluida gas-minyak
Identifikasi Perubahan Indeks Vegetasi dan Kaitannya Dengan Mineral Alterasi Menggunakan Citra Sentinel-2A Multi Temporal
Get PDFIndeks vegetasi merupakan parameter yang diperoleh dari citra satelit untuk menggambarkan aspek kerapatan vegetasi di suatu daerah. Kawasan Jember bagian selatan berada di daerah dengan kerapatan vegetasi lebat dan masuk dalam formasi vulkanik yang menjadi indikasi keterdapatan mineral alterasi. Alterasi mineral terbentuk dari proses ubahan pada mineral akibat adanya proses kompleks yang meliputi perubahan secara mineralogi, kimia, dan tekstur pada batuan. Tujuan penelitian yaitu untuk mengidentifikasi keterkaitan perubahan indeks vegetasi dengan keberadaan mineral alterasi. Untuk menghindari kesalahan pengamatan karena kawasan bervegetasi lebat, maka citra Sentinel-2A yang digunakan lebih dari satu waktu (multitemporal). Proses pengolahan data meliputi koreksi geometrik dan atmosferik, perhitungan NDVI (Normalized Difference Vegetation Index), dan observasi lapangan. Rata-rata nilai indeks vegetasi pada April 2021, Juni 2022, dan Juli 2022 masing-masing sebesar 0,5749, 0,6722, dan 0,6316. Persentase tutupan lahan dari tiga series data didominasi oleh kerapatan vegetasi tinggi sampai sangat tinggi dengan nilai di atas 70%. Jenis penggunaan lahan pada kerapatan vegetasi yang tinggi yaitu hutan, perkebunan, sebagian taman nasional, dan lahan pertanian. Mineral yang teridentifikasi antara lain kuarsa, kaolin, piroksen, plagioklas, dan lain-lain. Mineral alterasi argilik ditemukan di kawasan dengan kerapatan vegetasi yang sangat tinggi