Abstract
Lake Sibaya is the largest nearshore freshwater lake in South Africa. It is ecologically and socioeconomically linked to the human development agenda in the northeastern coastal region of the country. It is part of the iSimangaliso Wetland Park, the first proclaimed World Heritage Site in the country and the only water resource serving surrounding areas. However, Lake Sibaya is reportedly drying up rapidly for various reasons (e.g., commercial forestry), yet the extent and pattern of this drying are unidentified. Here, we used the Landsat satellite data series and the Digital Shoreline Analysis System (DSAS) algorithm to analyze the changes in the shoreline of Lake Sibaya between 1986 and 2020. The study results indicate that Lake Sibaya displayed major retracting changes from 70.6 km2 in 1986 to 49.5 km2 in 2020, with marked erosional changes in the regions of the southeastern basin and northern arm. This occurred with a net shoreline displacement of − 1338 m and an end point rate of − 39 m/year, averaging ± 6 m/year. Our results projected further lake retreat from 49.5 km2 in 2020 to 39.1 km2 in 2030. We observed vegetation growth on sandbanks separating the southeastern basin from the main system, threatening to isolate these systems entirely. Improved rainfall is expected to reconnect these basins because they rely heavily on groundwater recharge. Otherwise, activities served by the southeastern basin will be affected. We recommend further research to accurately quantify the levels of abstraction by different users, including fine-scale mapping of planted forests surrounding this lake.