Flood vulnerability assessment along the eThekwini east coastline, South Africa

Abstract

Coastal regions are physically and socio-economically important. The eThekwini coastal city in South Africa is particularly vulnerable to flooding due to climate change. Despite recurrent flood events, research that integrates the physical and socio-economic dimensions of vulnerability remains limited. Flood vulnerability assessments based on limited criteria and components may yield results that are neither sufficiently detailed nor accurate. Consequently, this study aims to develop an integrated flood vulnerability assessment (IFVA) approach using the Geographic Information System (GIS)-based Analytical Hierarchy Process (AHP) framework. A participatory approach, based on seven (7) key informant interviews and three (3) focus group discussions, was thematically analysed to supplement the GIS model output. Thirteen criteria, grouped under two vulnerability components (physical and socio-economic), were assessed. The criteria were weighted using the AHP framework and integrated to generate separate vulnerability indices. The integrated flood vulnerability map was then developed by combining the physical and socio-economic vulnerability indices. The results show that 56% and 5% of the study area are highly and very highly vulnerable to flooding, respectively. These areas are concentrated in informal settlement hotspots, particularly Umlazi and Dakota, and in low-lying areas around Durban Bay and the uMkomazi and Mbokodweni River catchments. Moderate vulnerability accounted for 34% of the area, whereas very low and low vulnerability zones represented 1% and 4.24%, respectively. Qualitative findings identified several key drivers of high flood vulnerability. These include historically disadvantaged communities, social inequality, limited community engagement, communication gaps, blocked drainage systems, and the expansion of informal settlements, particularly in the southern part of the study area. The study demonstrates that an integrated geospatial framework can enhance flood vulnerability assessment and support stakeholder decision-making for sustainable planning in the area.