Building Resilience: Analyzing Beira’s Drainage Network and Flood Management

The impact of failure mechanisms on flooding in informal settlements

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Abstract

This research analyses and evaluates the performance of the drainage system in Beira, Mozambique. It considers its formation, maintenance, failure modes and connections, to recommend improvements on its performance. The research identifies six primary failure modes - vegetation overgrowth, human interference, waste accumulation, sedimentation, underdimensioned structures and ’other’ - highlighting the disparities between technical design and real-world complexities. The study quantifies the presence of these failure modes by direct observations and transect walks, and uses hydraulic modeling software, D-FLOW FM 1D2D, to simulate their impact on inundation depths.

The results show that widespread flooding can be found even without failure modes. Additionally, it prioritises the risks of vegetation and human interference. Therefore, it recommends an increase of hydraulic capacity of a part of the system, proactive vegetation management, water level control, and community engagement in system management. It also underscores the importance of early land demarcation in urban planning, the implementation of flexible yet delineated canals, and the involvement of communities in flood adaptation.