TSUNAMI HAZARD MAPPING BASED ON COASTAL SYSTEM ANALYSIS USING HIGH-RESOLUTION UNMANNED AERIAL VEHICLE (UAV) IMAGERY (Case Study in Kukup Coastal Area, Gunungkidul Regency, Indonesia)

Abstract

The Kukup Coastal Area is located in the southern part of Java's coastal area, which has an active megathrust subduction zone. The dynamics of tectonic activities in this zone trigger earthquakes with various intensities. Some of these earthquakes can trigger a tsunami threatening human activities in this area. Therefore, a detailed study of tsunami hazards by integrating physical and socio-economic aspects needs to be done to estimate disaster risk and determine spatial planning in coastal areas. The objectives of this study are (1) to identify the coastal system and (2) to create a tsunami hazard map in the Kukup Coastal Area. Coastal systems can be identified by analyzing the physical and socioeconomic conditions. Physical conditions such as morphological and coastal typology can be extracted from Digital Elevation Model (DEM) from aerial photo processing. Socio-economic conditions such as land use analysis and tourism activities can be extracted from orthophoto, which is extracted from aerial photo processing using drones. The tsunami hazard can be analyzed using three modelling stages: earthquake source modelling, tsunami wave propagation modelling, and tsunami inundation modelling using Geographic Information System (GIS). The results show that the morphological conditions in the study area were dominated by the formation of conical hills with a firm lineament pattern causing the formation of elongated basins such as labyrinths. This basin is a place for developing socioeconomic activities, especially tourism, which can be seen from a large amount of built-up land area. The presence of these basins causes the tsunami inundation pattern to extend perpendicular to the shoreline, causing the tsunami inundation in the study area to extend as far as 2 km from the shoreline.