Urban Flood Vulnerability and Risk Mapping using Multi-Criteria Analysis in Mzuzu City, Malawi

This paper presents the results of the assessment of flood vulnerability of Mzuzu City using Multi-criteria analysis and GIS. Using a Weighted Overlay approach, physiogeographic variables that influence floods such as drainage density, elevation, slope, landuse/landcover and soil type, were integrated and ranked based on their importance. From this assessment, urban flood risk map for the City was derived. The results show that 12% of the total area (112 sq. km.) of Mzuzu City has very high risk of flooding, 29% has high risk, 41% has low risk and 18% has very low risk of flooding. Both very high- and high-risk zones are located in the low-lying and flat central part of the City. The Northern and Easterly parts are low risk zones while the southern part are very low risk areas. LU/LC changes have exacerbated the degree of vulnerability of the city. High population growth has led to changes in LU/LC patterns. Built-up Area/Settlement and Bareground/Paved have increased while Dense Vegetation and Dambo Land have reduced considerably. The adoption and use of the generated flood risk vulnerability map by authorities will help to quickly assess potential hazardous areas and the impact of flood hazard. It can further guide in the commencement of appropriate measures to reduce its impacts in pre-disaster and post-disaster situations. Keywords: Analytical Hierarchical Process (AHP), Geographic Information System (GIS), Landsat Images, Multi-criteria analysis, Reclassification, Weighted Overlay, Urban texture typology.