LAHAR FLOW SIMULATION BASED ON THE DIGITAL SURFACE MODEL (DSM) MOUNT SEMERU ERUPTION 4 DECEMBER 2021

• Main Author: Nabilah, Maudy
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/73551
• Institution: Institut Teknologi Bandung

<p align="justify">Lahar flows with large volume and high speed, including the eruption of Mount Semeru on 4 December 2021. The lahar flow will pass through objects in front of it, including vegetation and buildings. Lahar flow simulations often use DSM. This data was selected by considering the objects recorded in the DSM, which are the earth's surface and the objects on it (including vegetation and construction). However, there are still possible differences between the simulated lahar flow using DSM and the actual lahar flow traces. Therefore, by comparing these two flows, it can be seen how the effect of using DSM in simulating lahar flows. In this study, the data were used are DSM before the 4 December 2021 eruption, high-resolution satellite imageries after the 4 December 2021 eruption, and the base map of study area. The simulation process is carried out by conducting a hydrological analysis on the DSM, forming proximal hazard zone, and forming distal hazard zone. The lahar simulation was carried out with three (3) volume scenarios, those are 3 million m3, 6 million m3 and 26 million m3. Post-eruption high-resolution satellite imageries is used to delineate lahar flow trails. After that, the simulation results were compared visually with the existing lahar trails. The flow of the simulation results leads to the east of the peak of Mount Semeru. Based on the path of the lahar flow, the volume of 26 million m3 is the volume estimation with the least difference to the traces of existing flow. Meanwhile, based on the measurement of the width of the flow, the volume of 3 million m3 is the volume estimation with the smallest difference to the to the traces of existing flow. The total area of the settlements exposed to the flow of the simulation is 63,874.74 m2. The width of the river border obtained in this study is about 716 m from the river thalweg. The results of the lahar flow simulation in this study are expected to be useful in disaster mitigation activities around Mount Semeru and in predicting the risk of disaster that will occur in the future.