2D SIMULATION OF DESIGN DISCHARGE IN FLOOD HAZARD SPATIAL ANALYSIS USING HEC-RAS, (CASE STUDY MATA ALLO SUB-WATERSHED, ENREKANG, INDONESIA)

Uca SIDENG , Hamzah UPU , Nurul Afdal HARIS , Dwi RAHMAYANA

DOI: 10.21163/GT_2023.182.01

ABSTRACT: Indonesia is one of the countries frequently hit by hydrometeorological disasters. Flood is one of the disasters that often occurs in Indonesia. Especially for the Enrekang area which is traversed by the Mata Allo River. With topographical characteristics and land use that has the potential to cause flooding and high rainfall. It will harm activities in the watershed area. In reducing the impact that occurs, it is necessary to identify and map flood-prone areas as initial information on flood control. This study aims to determine the distribution and level of vulnerability to flooding in the Mata Allo sub-watershed using 2D HEC-RAS simulations. By utilizing annual rainfall data, the Nakayasu HSU method is applied to generate design discharge values to be used in flood simulations. The simulation results show that there are five classes of flood hazard levels which show the uniformity of flood vulnerability levels in each return period. The average level of vulnerability is in the very low range of ±9.60 Ha, in the low range of ±8.8 Ha, medium vulnerability is in the range of ±13.63 Ha, high vulnerability is ±23.58 Ha, and extreme vulnerability is ± 25.71 Ha. The area that is mapped is an area that is often affected when a flood occurs. As a result, the use of this approach can provide an overview of the distribution of flood-prone areas.

Keywords: spatial analysis, flood, Nakayasu HSU, discharge, simulation

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