Geospatial analysis of shoreline change of ethekwini coastline from 1990 – 2023

Abstract

Coastal areas are dynamic environments impacted by both natural and anthropogenic processes. Hence, it is important to continually and accurately monitor these areas for change and develop coastal management strategies. The present study uses the Digital Shoreline Analysis System (DSAS) and satellite imagery to assess the changing dynamics of the Durban coastal stretch of the eThekwini Municipality from 1990 to 2023. Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR) were calculated in DSAS to analyse the shoreline changes. The analysis revealed significant variations in erosion and accretion across the coastline. The average shoreline movement was 2.49 m in the north and -7.42 m in the south, indicating predominant erosion in the southern regions. Specifically, 53.85 % of transects in the north and 71.9 % in the south were negative distances, highlighting erosion areas. The EPR analysis indicated an average annual change rate of 0.09 m/year for the north and -0.22 m/year for the south, with erosion rates averaging -2.05 m/year in the north and -1.21 m/year in the south between 1990 and 2023. The LRR method corroborated these findings with annual changes of -0.01 and -0.37 m/year, respectively. High erosion rates were concentrated in areas such as Umhlanga Rocks and Beachwood, while engineered structures contributed to accretion in parts of Durban North. Conversely, the southern coastline, particularly around Amanzimtoti and Isipingo, experienced more erosion than accretion due to fewer protective structures. This study highlights the dynamic nature of shoreline changes along the Durban coast. Understanding these trends is essential for effective coastal planning and management and building resilience against the multiple hazards ravaging coastal communities.