GEOTHERMAL MANIFESTATIONS MAPPING BASED ON REMOTE SENSING AND VEGETATION STRESS ANALYSIS IN ULUBELU REGION, LAMPUNG

• Main Author: Dwijati Astika, Solana
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/78907
• Institution: Institut Teknologi Bandung

In order to achieve net zero emissions by 2060, Indonesia's government is pushing ahead with the development of renewable energy. There is considerable geothermal energy potential in Indonesia, but it has so far not been fully exploited. The Ulubelu Geothermal Field has a water-dominated volcanic geothermal system. It has been developed since 2012 by Pertamina Geothermal Energy (PGE) and is capable of supplying 25% of the electrification of Lampung Province. The presence of fluids or gases in an area as a possible manifestation of the geothermal system can lead to vegetation stress. With the possibility of covering vast areas in a relatively short time, the use of remote sensing techniques to detect geothermal manifestations such as surface temperature anomalies, altered rocks and vegetation stress is likely to improve the efficiency of the preliminary phase of geothermal exploration. This research aims to present a general overview of geothermal exploration by utilizing a combination of remote sensing techniques followed by on-site validation. The data sources for this study encompass Sentinel 2B and ASTER satellite imagery, DEMNAS, magnetic susceptibility data, and ferns chlorophyll content. The research methods comprise remote sensing analyses, specifically band ratio and mineral DPC analysis, NDVI assessment, LST analysis, and lineament analysis. These analyses are subsequently corroborated through field validation, involving measurements of ferns' chlorophyll content, magnetic susceptibility, and on-site observations. The LST analysis of ASTER imagery reveals the presence of four geothermal manifestation sites in the Pagaralam and Datarajan areas which were confirmed to be hot springs, fumaroles, solfatara, altered rocks, mud pools, and spouting springs. NDVI band ratio analysis of Sentinel-2B imagery can identify the distribution of vegetation stress (0.1 ? NDVI ? 0.4) in the Ulubelu area, with a northwest – southeast trend. A moderate positive correlation (R = 0,66) between the magnetic susceptibility value and in-situ chlorophyll content in the study area is shown, which indicates that the presence vegetation stress may serve as an indirect indicator of geothermal manifestations. The existence of geothermal manifestations in the research area is controlled by fault structures which create permeable zones as pathways for hydrothermal fluids to alter the rocks near the geothermal manifestations, thus affecting the physiological functions of plants, which then identified as vegetation stress.