Characterization and Prediction of Flood Risks in the Congo River Basin

Código

I-EBHE0050

Autores

Bola Bosongo Gode, Mark Trigg, Paul Bates, Raphael Tshimanga Muamba, Jeff Neal, Lauwrence Hawker, Vincent Lukanda Mwamba

Tema

WG 1.04: From local to large scale human-water dynamics

Resumo

The Congo River Basin is unique among large rivers because of its almost circular course, which crosses the equator twice, and a feature of the system that is a significant contributor to the formation of the river?s double-peaked annual flood pulse. Our measurements and modelling of the Congo?s catchment hydrology and hydraulics have helped uncover the mechanisms behind the double annual flood pulse and have enabled the first characterization of flood patterns across the basin to determine where in space the switch from a monomodal to a bimodal flood pulse occurs. In contrast to the bimodal flood pulse seen along the Congo main stem, our work showed that only a unimodal flood pulse is produced by the Northern and Southern tributaries contributing flow along this reach. We, therefore, conclude that the bimodal flood pulse is generated by the flood waves from the contributing catchments arriving at the main stem at different times and combining either synchronously or asynchronously with the main stem flow peak. Given that 100 million people in the Congo Basin rely on Congo River, information on flood patterns supports numerous river-based activities and services. Timing of floods has an effect on floodplain farming systems as well as the livelihoods of inhabitants who modify their agricultural and floodplain activities to correspond with the rise and fall of the flood wave. The flood pulse can affect biotic composition, nutrient transport, fish production, animal habitat creation, floodplain construction and soil fertility restoration. Flood risk planning and preparedness are required not just in ?hotspot areas? but also throughout ?hot seasons?. Our measurements and modelling of the Congo?s catchment hydrology and hydraulics have therefore also helped to predict flood risk. Flood risk analysis has led to the creation of hotspot maps by considering areas in which high occurrence of flooding coincides with high exposure based on flood hazards and risk analysis. We have been able to characterize the Congo?s flood frequency, the Generalized Extreme Value (GEV) and Log-Pearson Type III (LP3) distributions were found to be the most suitable for flood frequency analysis in the region. Lastly, through future projections, the study suggests that flooding could increase under the Representative Concentration Pathways (RCP) 4.5 and 8.5 scenarios, along with a potential shift in the timing of floods during the 21st century (2020?2099). Flood characteristics and risks established in this study can be applied to various aspects of flood management, including agriculture, river ecosystems, water reservoirs and dams, hydropower, and risk management policy. This work contributes to the resolution of flood-related issues for humanitarian emergencies and community resilience in the Congo Basin.