Flood Mapping Potential Areas Using HEC-RAS Software (Case Study: Kota Lama of Semarang)

Abstract

Semarang has experienced floods every year, with a peak in the rainy season. At the end of 2022, there was heavy rain which caused the East Flood Canal River to overflow. As a result, the floods inundated several areas in Semarang City, including Kota Lama of Semarang. This study aims to determine the value of the designed discharge, the area of the flood inundation that occurred and the flood inundation map for return periods of 2, 5, 10, 25, 50 and 100 years. The methodology of this research consist of hydrological analysis, hydrological modelling with HEC-HMS and hydraulics modelling with HEC-RAS and integration with ArcGIS. In this study, it was found that for a return period of 2 years the planned flood discharge value was 153.7 m3/second with an inundation area of 406 Ha and a flood height of 17 cm to 68 cm, up to a return period of 100 years with a planned flood discharge value of 455.7 m3/second with an inundation area of 796 Ha and a flood height of 83 cm to 180 cm.