In many Sub-Saharan African cities, urban flooding is a major concern. This issue is made worse by rapid urban growth and climate change. The existing drainage systems in these cities often struggle to handle heavy rainfall. One key factor that makes this problem even worse is the buildup of sediment and solid waste in these systems. Yet, not enough research has looked into how this buildup affects the performance of urban drainage systems during extreme weather conditions.

In the upper Lubigi catchment of Kampala, a study focused on this very issue. The research combined high-resolution rainfall data with water level observations and field data. This combination was used to calibrate and validate a model. The findings were clear: three specific locations were responsible for over 50% of the flooding in the catchment. This highlights the critical points where interventions could make a big difference.

The study also simulated what would happen if these key points were almost completely blocked by sediment and solid waste. The results were striking. For severe storms that happen once every 50 years or more, flood volumes increased by up to 40%. For less severe storms that occur more frequently, the increase was even more dramatic, reaching up to 105%. This shows just how much of an impact sediment and solid waste can have on urban flooding.

One of the key takeaways from this research is the importance of using detailed rainfall data in flood modelling. This allows for more accurate predictions and better planning. Additionally, the study emphasizes the need for better management of urban drainage systems. This includes regular maintenance and effective management of solid waste and sediment. By addressing these issues, cities can become more resilient and better prepared for future flooding events.

The study also highlights the need for a broader approach to water management. It's not just about building bigger or better drainage systems. It's also about keeping these systems clear and functional. This means investing in regular maintenance and waste management. It also means educating the public about the importance of keeping drains clear. After all, everyone has a role to play in preventing urban flooding.

Urban Flooding: The Hidden Culprits in Kampala's Storms

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