Modification of Flood Hazard Assessment in Pemaluan River: Case Study of Pemaluan Village, Penajam Paser Utara Regency

Abstract Flooding occurs when river water overflows its channel or inundates low-lying areas without adequate drainage. Heavy rainfall, reduced drainage or river capacity, topography, land use change and tidal influence are all factors that cause flooding. The socio-economic and developmental impacts of this disaster in Indonesia are significant. One of them is in Sepaku District, Penajam Paser Utara Regency, East Kalimantan Province. The Sanggai Watershed is a watershed located in Penajam Paser Utara Regency, East Kalimantan Province, where there is an area that has been designated as the new National Capital to replace Jakarta. The Sanggai watershed has 7 (seven) rivers that flow into Balikpapan Bay, namely Trunen, Semuntai, Sanggai, Sepaku, Semoi, Pemaluan, and Baruangin. Pemaluan Sub Watershed, with an area of 124.43 km 2 is in the Sanggai Watershed and is drained by the Pemaluan River. The Pemaluan River often experiences flooding due to high rainfall intensity, long rain duration, low culvert capacity, river narrowing and the absence of an adequate drainage system that inundates residential areas, provincial roadside areas resulting in environmental, community and economic losses. Especially in terms of flood management, the above problems need attention. Since there is no previous research that discusses flood hazard assessment in the area, this study aims to conduct a flood hazard assessment with an approach that emphasizes inundation review in detail quantitative flood hazard classification with flood hazard mapping, flood inundation will be simulated with 2D flow area and unsteady flow data availability using HECRAS 6.5 software. Referring to the NADM parameter criteria with a high category which has an area of 6.22 Km 2 , while in MPWH with a very high category which has an area of 3.46 Km 2 .