Design of a sustainable hydraulic structure for flood control in Rubyiro catchment with focus on Katabuvuga sub catchment

Abstract

Floods are natural events that mainly happen when the river catchment receives greater water than usual amounts (for example through rainfall or melting snow). The river cannot cope and this extra water causes the level of the water in the river to rise and a flood to take place. This flooding may take place at any point along the river course and not necessarily at the place where the extra water has entered. Most of countries in Africa are regularly affected by severe and often multi-year disasters including landslides and floods. Rwanda is among countries which face floods disasters because of its topography. Rubyiro catchment especially Katabuvuga sub catchment is not left out of the effect of this global disaster and it is located in south-west of Rusizi District Western Province. The Katabuvuga sub catchment (39.68 Km2) through its main river Katabuvuga (21.67 Km) is one of the major flood prone areas in the country, where almost every year flood events are recorded and its consequences have been evaluated in Bugarama Valley especially on rice farming. The aim of this study is to design a sustainable hydraulic structure for flood control in Rubyiro catchment with focus on Katabuvuga sub catchment. Daily rainfall data from January 2011 to December 2019 have been collected from two meteorological stations; the Kamembe airport station and Bugarama station. The maximum rainfall intensity was found to be 2.3 mm per hour which was observed on the 07th March 2016. The peak runoff water discharge has been calculated by using the rational method and its prediction in 30 years has been calculated by using the linear model (Q= 10.093 m3/s). For a long term sustainable flood control solution for the Katabuvuga River of the Katabuvuga sub catchment as well as in the Bugarama Valley, a multipurpose embankment dam have been proposed. The proposed multipurpose embankment dam, once applied will contribute not only to the flood control observed in this sub catchment but also in other purposes like fishing, support existing irrigation systems, recreation among others for the development of that area.