Flood risk assessment of River Nyamwamba in Kasese District

Abstract

River Nyamwamba originates from Mountain Rwenzori flowing through Kasese district pouring its waters in lake George. Over the years, frequent floods have posed a great threat to communities in the catchment especially in Kilembe town where it has destroyed bridges, houses, hospital facilities, killing and displacing people. This study aimed at carrying out a flood risk assessment through rainfall data analysis, GIS, hydrological and hydraulic modelling. Hydrological modelling was done with HEC-HMS using Curve Number method as loss method and Muskingum for routing to simulate run-off from the catchment. Flow simulations were forecast for various return periods producing flow hydrographs for each event. HEC-RAS was used to carry out hydraulic modelling from the run off data and subsequent flood plain maps developed for each flood event. A flood plain management programme the various flood plain zones as then developed regulating and restricting activities that can be carried out with the catchment.