Modelling flood risks and providing mitigation strategies : a case study of Nakivubo drainage channel

Abstract

Flooding in Kampala has increasingly become a major environmental and infrastructural challenge, primarily driven by rapid urbanization, inadequate drainage systems, and erratic rainfall patterns. This study focused on the Nakivubo drainage channel, the city’s primary storm water system to model flood risks and assess potential mitigation strategies. Using Hydrologic Engineering Center's River Analysis System, the project simulated flood inundation scenarios for 10-year and 25-year return periods. Cross-sectional and terrain data were obtained using a Real Time Kinematics Global Positioning System (RTK GPS) and Digital Elevation Models (DEMs) from Kampala Capital City Authority. Key mitigation strategies investigated included cleaning and smoothening the channel to reduce friction and increasing channel size to enhance conveyance capacity. Results showed significant flood risk along the channel under both return periods, with improved channel conditions showing a clear reduction in flood depth and velocity. The study concludes that integrating flood modelling tools with urban planning offers effective solutions to urban flood challenges and can guide strategic interventions in Kampala’s drainage infrastructure.