Coastal risk is a reality globally, with KZN being no exception. As such we need to plan for and better manage in light of coastal risk. In South Africa, one of the approaches to this is the development of coastal management lines (CMLs), which is a line which indicates a ‘buffer zone’; seaward of which development is controlled.
The determination of CMLs requires a number of considerations and inputs, one of the key inputs is that of coastal risk – understanding the physical risk along the coast in light of climate change (sea-level rise), long and short term coastal changes (erosion; extreme events) and natural coastal dynamics (waves climate).
The key components in the determination of the coastal risk line
The risk lines determined considered three time horizons:
Drawing the risk line
- Step 1: Profiles were drawn every 200m along the coastline in the dominant wave direction (SE).
- Step 2: The -15m CD contour line based on the SANHO admiralty charts was assumed to be equal to the depth of closure
- Step 3: The position of the estimated wave run-up level for each SLR Scenario was mapped at each profile location.
- Step 4: The position was further shifted landwards based on the short-term erosion buffer
- Step 5: For each of the Scenarios, the estimated positions of the coastal processes along the profiles were plotted and connected to form the Preliminary Coastal Processes Line.