KAJIAN RISIKO BANJIR SUNGAI BIYONGA DI KABUPATEN GORONTALO

Abstract

Almost all areas in Gorontalo Province are flooded every year. One of the affected areas is Limboto District, Gorontalo Regency. This flood causes residential areas, office buildings, agriculture, public facilities to be submerged and threatens lives. A flood risk study is needed to obtain an index of threats, vulnerabilities, losses and capacities that arise due to flood disasters. In this study, BNPB Regulation No. 2 of 2012 is used as a guideline for determining the index and Flood Risk Level. Regional rainfall is calculated using the Thiessen Polygon method, while the planned flood discharge uses Q25th with the SCS method. Discharge data validation is carried out by overlaying inundation and flood height data with flood event data obtained from BWS Sulawesi II Gorontalo. The 25-year return period flood in the Biyonga River is 129.16 m3/s. The results of hydrological calculations are used in flood modeling using HEC-RAS 2D. The modelling result map is a map of the flood inundation area of ??136.12 ha in 4 sub-districts, namely Hepuhulawa, Hunggaluwa, Kayu Bulan, and Kayu Merah. The results of the loss and capacity index scoring showed that Hunggaluwa sub-district has the highest level of flood threat compared to the other three (3) sub-districts. Based on the assessment of the level of threat, loss and resilience, the highest level of flood risk is in Hunggaluwa Sub-district is a high-risk.