Flood Impact Assessment Using HEC-RAS and GIS Techniques Dinder River, Southeast Sudan

Dinder River is largest tributary of the Blue Nile. It is seasonal river that flows from June to November and reaches its high peak in September. Frequently, the water level exceeds the normal height causing over bank flow and consequently floods. The floods generally ring about losses properties and crops close to river banks. This study is attempts to figure out the river flow behavior and find out the aerial extent of inundated lands in four flooding seasons. The investigated area is located in Sennar State, SE Sudan. Discharge data collected over the period from 2015 to 2018 and Digital Elevation Model (DEM) have been used to model the River flow regime, while land cover data was used to determine the affected LU/LC types in the area. HEC-RAS software was used to create 2D unsteady flow model in order to simulate Dinder River flooded area in four seasons. The largest flooded area extent in each season was used as input in GIS environment for further spatial analysis. Statistical computation for the affected area and consequent analysis revealed that: the affected urban area in 2018 was around 28.152km2, in 2017 was 29.205 km2, in 2016 was 16.531km2, and in 2015 was 10.422km2. Similar calculations were carried out for the other LU/LC types. According to the present study, the year 2017 witnessed the largest extent of flooding in the area.