Identification of spatial potential flood-prone area using topographic wetness index under the digital elevation model of Kr. Keureuto watershed, North Aceh.

Abstract Floods are the most frequent disaster events in Lhoksukon, resulting in significant losses and community and environmental damage. Floods are generated by several factors, consisting of hydrometeorological, topographical, geological, soil, and human activities. Topography is a key controlling factor in flood initiation. Topographic analysis for detecting flood susceptibility, especially flood inundation, can be conducted using the TWI. The research aims to identify the potential spatial distribution of flood-prone areas based on TWI and assess the model accuracy using the ROC-AUC method. A case study was conducted in the Kr. Keureuto watershed. of North Aceh. TWI analysis is based on the topography of an area denoted by extracting DEM using GIS to create slope, flow direction, and flow accumulation. Higher TWI values are associated with higher flood susceptibility. The results show that the value of TWI is approximately 1.571-27.147, showing that more than 20% of area are potentially flood inundations with high and very hight rating of flood susceptibility. Furthermore, based on the analysis using field observation flood is obtained the AUC value of 71,60%. It can be concluded that the spatial model of flood-prone using TWI is good and effective for determining flood prone region in the Kr. Keureuto River basin