Flood Susceptibility Analysis Using Frequency Ratio Method in Walanae Watershed

Abstract

Flooding is a type of natural disaster that has occurred frequently in Indonesia since 2012-2022 and occupies the second highest position compared to other types of disasters released by the Indonesian National Disaster Management Agency. In South Sulawesi, flooding occurs every year, especially in areas affected by watersheds, such as the Walanae watershed. Indications of flooding causes include land change and overflows from rivers and lakes. Identifying factors affecting flood occurrence is necessary for the region's watershed management and development planning. This study was conducted to determine the factors that most influence the occurrence of floods and map the level of flood susceptibility in the Walanae watershed using the Frequency Ratio method. The causal factors analyzed in this study are rainfall, Topographic Wetness Index, elevation, slope, land cover, and distance from the river, which are then processed to obtain the frequency ratio value. The study results show that the most influential factor is land cover as a water-absorbing medium, with FR probability values of 4.27 and 3.31 in the water body and rice field cover classes. Land use direction needs to be followed up in the Walanae watershed, such as direction and correction of the spatial pattern plan improvements, especially in the spatial pattern of settlements and agricultural land that contribute to high flood impacts.