Application of 2D numerical simulation for the analysis of July 2020 North Luwu flood

Abstract

Massamba is a district in North Luwu that is continually flooded by the Massamba river. The flood lasts for several days with tons of suspended materials affecting important places in the city, drowning people, and swamping arable land. Two-dimensional (2D) numerical simulation Hec-RAS is one of the most popular hydraulic models which is proved to be an important tool for analyzing and understanding flood events. The new version of Hec-RAS (5.07) was released and including 2D models capabilities. This study applied the new Hec-Ras version 5.07 to simulate the July 2020 flood in North Luwu. The flood simulate shows good results compared with the observation of the satellite image of the flood event. The simulation result provides some information like velocity, depth, and inundation area. Over the flooded area the depth is lower than 3,88 meters, velocity lower than 2,4 m/s-1, and swamping over 2,3 square kilometers of Massamba city. The flood depth allows identifying areas exposed based to hazard levels based. The simulation result validated by comparing the simulation result to the satellite image and calculating the root mean square error (RMSE) of water depth from the simulation result and during a flood event. The validation result shows that the determination coefficient R2 is 83,66%. The study shows the applicability and the value of the 2D capabilities Hec-RAS for flood studies.