DEMNAS: A Recently Released Nation-Wide Digital Elevation Model from the Indonesian Government and Its Implication for Geothermal Exploration – Study Case of Gunung Endut Geothermal Prospect, Banten Province, Indonesia

Abstract

Digital elevation model (DEM) is very useful for geothermal exploration in Indonesia. It is very useful when the ground geodetic survey is not available or hard to implement in dense forest. Another condition is when Airborne LiDar survey might be too expensive for initial exploration stage. The most common DEM used for geothermal exploration in Indonesia is DEM Shuttle Radar Topographic Mission (SRTM) that has spatial resolution 3 arc second (±90m). Recently, Indonesian Geospatial Information Agency has released DEM Nasional (DEMNAS), an open-access DEM with spatial resolution of ±8.25 meter. Similar to SRTM, the DEMNAS could be implemented in various applications, including geothermal exploration. In this study, we implemented DEMNAS in our scientific exploration work in Gunung Pancar Geothermal Prospect, Banten Province, Indonesia. Previously, we use SRTM to guide our geological interpretation, particularly when interpreting lithological boundaries and geological structures. We re-interpreted the geological structures and lithologies using DEMNAS as digital elevation model and compare the result with the previous interpretation. For the lithological interpretation, DEMNAS showed better result compared to DEM SRTM due to the textural variations that can be better observed in higher spatial resolution. Smaller geological structures can be interpreted with more confidence compared to when using SRTM. However, we also find that SRTM is still usefull when interpreting major geological structures. From this comparison, we believe that DEMNAS could be a useful tool for geothermal exploration in Indonesia. DEMNAS could replace SRTM for general purpose, although SRTM still needed to complement DEMNAS for specific task.