Physical vulnerability of buildings to flooding in Lilongwe City, Malawi

TL;DR

This study examines how different building types in Lilongwe, Malawi, are affected by flooding, finding that construction materials and design significantly influence vulnerability.

Contribution

The study provides localized insights into physical flood vulnerability using statistical analysis in low-income urban settlements.

Findings

Building typology and floodwater depth significantly influence physical vulnerability.

Buildings with fired bricks and cement floors have lower vulnerability.

High foundations and protective measures reduce flood vulnerability.

Abstract

Research on flood vulnerability has mainly focussed on social, economic and human vulnerability and the few studies that have attempted to analyse the physical vulnerability of buildings to natural hazards (seismicity and floods) have been done at the subnational spatial scale resulting in generalised vulnerability outcomes. Additionally, most of the studies used models to analyse vulnerability which are known for uncertainties in the results. This study investigated the physical vulnerability of buildings to flooding in low-income settlements of Biwi and Kawale 1 in Malawi’s capital city, Lilongwe. Statistical Package for the Social Sciences 20 was used for descriptive statistics frequency, cross-tabulation and chi-square analysis to correlate exposure factors and the physical vulnerability of buildings. The study found that exposure factors variably influenced the physical vulnerability of individual building types, and that building typology and floodwater depth were important factors. Irrespective of their location, buildings constructed using fired bricks with cement mortar walls and cement floors had low vulnerability while buildings constructed using fired bricks in mud mortar walls and cement floors had high vulnerability. Buildings with protective measures such as high foundations had low vulnerability. The chi-square correlation test showed that the physical vulnerability was influenced by building typologies and floodwater level with a significance value of 0.001 (p < 0.001) and 0.004 (p < 0.005), respectively. Rather than urban planners and disaster management officials emphasising stream reserves as a preventive measure, advocating for the construction of buildings using flood-resistant materials and with high enough foundations in flood-prone areas should be considered central to urban flood risk reduction. Flood vulnerability studies should be conducted in other flood-prone cities of Malawi to support effective citywide urban planning and disaster risk management.

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