Flood hazard assessment of River Semliki in Ntoroko district, Uganda

Abstract

The semliki catchment basin model (32674.8km2) was delineated using HEC GeoHMS in ArcGIS 10.4.1 environment. Hydrological modeling was done using HEC HMS 4.2.1 software in which control specifications were defined and in the meteorological model, design storm parameters such as 10, 25, 50 and 100-year design storms were input that generated design flood discharges of 549.3, 1574.4, 3623.2 and 7284.4 m3/s respectively. Hydraulic modeling was carried out using HEC RAS 5.0.3 software that yielded flood inundation depth at the Bweramule gauging station of 1.500m, 3.202m, 8.171m and 8.771m for the simulated 10, 25, 50 and 100-year return period floods respectively. Flood hazard maps developed for each flood event showing the extent of the flood prone areas using the RAS mapper. Then flood plain management programme was developed on the proper use of the flood plain to minimize on the damage caused by the floods.