摘要：A river is a naturally occurring flow system that flows from upstream to downstream. Rivers have many benefits. Similarly, rivers have a negative impact if rainfall is high. It can lead to catastrophic flooding. Flooding often occurs along the central roads of Padang City when it rains, especially in the Maransi and Aie Pacah areas. The purpose of this study is to estimate the height of water level by using software HEC – RAS and estimate areas that have the potential for flooding in conditions before and after river normalization by using the software Arc-GIS. Data collection is carried out to achieve this goal, namely the maximum daily rainfall data, Digital Elevation Model (DEM) data obtained from the processing of aerial photo data, and cross-sectional data of the river. Then, a numerical simulation is performed to estimate the height of the water level, and then a numerical simulation is performed to determine the extent of the flood area. The results of this study are in the form of flood areas in conditions before and after river normalization with a period of 25, 50, and 100 years that can be used to see the effectiveness of river normalization work in the river.
