Integrated Assessment of Coastal Erosion and Flood Vulnerability in Durban, South Africa, Using Geospatial Techniques.

Abstract

Coastline erosion and flooding pose serious threats to coastal settlements, particularly in rapidly urbanising regions where climate change is exacerbating these hazards. This study aims to assess the spatial vulnerability to erosion and flooding across the 664.42 km 2 Durban coastline using complementary geospatial techniques. The Digital Shoreline Analysis System (DSAS) and Analytical Hierarchy Process (AHP), supported by field observations, were used. The results show that approximately 41% of the coastline is highly susceptible to erosion. The flood vulnerability assessment applied eight (8) physical and three (3) socioeconomic criteria, and a consistency ratio of 0.08. Approximately 369.00 km 2 (56%) and 214.65 km 2 (32%) of the coastal area are moderately and highly vulnerable to flooding, respectively, while 6.71 km 2 (1.01%) is very highly vulnerable, with critical hotspots concentrated in low-lying coastal areas. Low-vulnerability areas accounted for 74.06 km 2 (11.15%). However, there was a strong spatial overlap between high erosion and flood risk in Umlazi, Durban Bay, the Umgeni, and the uMkomazi estuaries, which were among the areas affected by the April 2022 floods. In these areas, shoreline retreat and encroachment of informal settlements have diminished the natural protective features of coastal dunes, wetlands, and beach width, exposing the population to hazard impacts. These findings highlight the urgent need for stricter implementation of the Integrated Coastal Management Act to address the interconnected risk of erosion and flood hazards in the area. These findings are particularly useful to disaster managers and coastal engineers in supporting spatial decision-making to enhance the resilience and sustainable planning of coastal communities in the area.