Dynamics of the Banks of the Tsiémé River in Brazzaville (Congo): Urbanization, Vulnerability to Flooding, and Sustainable Management Strategies

Abstract

Purpose: This study analyzes the dynamics of the banks of the Tsiémé River in Brazzaville (Republic of Congo) in order to assess the influence of unplanned urbanization on vulnerability to urban flooding. It examines the interactions between hydro-geomorphological transformations of the channel, occupation of the riparian corridor, social exposure, and land governance, with a view to guiding the sustainable management of urban river spaces.

Methodology: A descriptive and analytical approach based on a mixed methodology was adopted. The study focused on a 4,013-meter urban section located between the districts of Ouenzé and Talangaï. Primary data were collected through household surveys, institutional interviews, field observations, and GPS surveys. Multi-date satellite images, topographic and rainfall data, and planning documents were used to supplement the analysis. Hydrogeomorphological, spatial, social, and institutional indicators were processed using statistical tools and geographic information systems.

Findings: The results reveal a marked contraction of the channel and increased bank erosion, reducing hydraulic capacity and promoting flooding. Significant occupation of the regulatory strip and loss of riparian vegetation weaken natural hydrological regulation functions. Flooding appears to be recurrent and socially impactful, with high exposure of riverside households. Despite the existence of a regulatory framework, its application remains partial.

Unique Contribution to theory, Policy, and Practice: The study demonstrates that flood vulnerability along the Tsiémé River is the result of interactions between physical dynamics, urban pressure, and institutional weaknesses. It highlights the need for integrated flood risk management and nature-based solutions to strengthen the resilience of urban river corridors.