Abstract
The aesthetic appeal of beaches has made coastal properties prime sites for development, particularly in areas that are iconic tourist destinations. However, in many places, this development has been mismanaged and is within the littoral active zone, too close to the beach. Coastlines normally retreat landwards as sea levels rise, but with current development trends, beaches are now trapped in a coastal squeeze. We aimed to determine the effect of sea-level rise on sandy beaches in KwaZulu-Natal (KZN), South Africa, using a GIS-based coastal recession model that we derived from Bruun's rule. All analyses were calculated for a high, medium and low scenario of both sea-level rise and development. We also tested the efficacy of a proposed 10-m contour setback line. Unconstrained beaches in northern KZN showed the greatest predicted retreat because they tended to be dissipative. However, no beach loss was predicted because the beaches could respond naturally by retreating landwards. More developed coastal sections showed a greater predicted loss of beach area, particularly where development was very close to the beach, or was protected by sea walls. The magnitude of the predicted retreat, development at risk of damage, and beach loss all increased with both increasing development and sea-level rise, indicating that development scenarios are as important as the climate change scenarios. Further, a 10-m contour was not completely effective as a setback line, even for a low sea-level rise scenario. The loss of beach predicted by this model has a number of negative ecological implications which suggest that coastal squeeze not only threatens to compromise the resilience of the coastal ecosystem, but that it also carries negative socio-economic implications because beaches are key draw-cards for tourism. We highlight the importance of using spatial-data techniques (such as GIS modeling) to motivate strongly for beach conservation, and to promote sensible coastal development strategies behind scientifically-determined setback lines.