A geospatial approach to assessing shoreline change dynamics along the eThekwini coast of South Africa

The eThekwini coast represents a critical hotspot of vulnerability to coastal hazards, particularly erosion and flooding. However, studies assessing historical shoreline change in eThekwini over the past four decades remain limited. The objective of this study was to assess and quantify shoreline change dynamics in eThekwini using geospatial techniques. Satellite acquired imagery from 1984 to 2024 were process in ArcGIS 10.8 using the Modified Normalised Difference Water Index (MNDWI) and the Digital Shoreline Analysis System (DSAS v6.0). The study quantify shoreline change using established statistical metrics i.e. Net Shoreline Movement (NSM), End Point Rate (EPR), Linear Regression Rate (LRR), and Weighted Linear Regression (WLR). The results show that 57.45 % of the shoreline was accretional while 42.55 % were erosional. However, the long-term accretional trend is likely to shift towards erosion, as the overall change rate of −1.03 m/yr consistently exceeds the ± 0.66 m/yr uncertainty threshold, reflecting the combined influence of urban development, climate change and sea level rise impacts on the coast. Accretion dominated Reg-1 and Reg-4, whereas Reg-2 and Reg-3 experienced statistically significant erosion beyond uncertainty. The erosional hotspots were largely concentrated near major rivers including Umgeni, uMdloti, and uMkhomazi river mouths. These patterns strongly correlate with the changes in land use, coastal infrastructures, damming, sand mining, and extreme weather events affecting the coastal city. These results provide actionable evidence for coastal risk management by identifying erosion hotspots, informing municipal setback lines, guiding risk-based land-use planning, and prioritising adaptation measures under South Africa’s Integrated Coastal Management framework (ICM Act No. 24 of 2008, amended Act No. 36 of 2014).Therefore, this study advocates a transformative approach that combine hybrid engineering and nature-based solutions to reduce human vulnerability and provide essential baseline data to support adaptive coastal management, and disaster preparedness to enhance coastal resilience in eThekwini.