Spatial Modeling of Volcano Merapi Lahar Flow Post 2010 Eruption in Krasak River for Hazard Zone Prediction

This study aims to model lahar flow from Volcano Merapi in the Krasak River following the 2010 eruption. The spatial modeling results of lahar flow are used to identify and predict lahar hazard zone. The lahar flow modeling is conducted using the Laharz toolbox, utilizing DEMNAS data, and lahar volume scenarios based on historical lahar volume data for the Krasak River from 2011. Remote sensing data, specifically Sentinel-2 imagery, is used in this study with interpretation methods to derive river hydrology information, which serves as one of the validation measures for the Krasak River flow. The model is developed based on predetermined volume scenarios: Scenario I with an initial volume of 125.000 m 3 , Scenario II with doubled volume of 250.000 m 3 , Scenario III with lahar volume of 500.000 m 3 , and Scenario IV with lahar volume of 1.000.000 m 3 . The model validation is conducted using the Mount Merapi Disaster-Prone Area Map. The resulting model is applied to predict hazard zone using a buffer method along the river, with specific distances defined. The model results indicate that as the lahar volume scenario increases, the lahar flow model can impact the prediction of lahar hazard zone.