Civil Engineering May 2022 | Vol 30 No 4

Civil Engineering May 2022 15 therefore essential to have a systematic understanding of the physical processes that drive shoreline change and what can be done to mitigate its impact. For example, along Durban’s coastline, large waves generated by wind interaction with the ocean surface are associated with stationary low-pressure weather systems to the southeast of KwaZulu-Natal. These low-pressure systems generate large waves and swells that travel long distances before arriving at Durban’s beaches. When the large waves reach the coast, they rapidly erode a beach and cause sig- nificant damage to infrastructure in the short term. The severity of this damage depends on the height of the waves, the direction they come from, the duration of the large waves and other local factors. NEW METHODOLOGY Changes to wave behaviour due to climate change will directly impact shoreline change. Dr Justin Pringle, who heads up the Environmental Fluid Mechanics Lab at UKZN, has developed a new coastal engineering design method that can incorporate the effects of climate change. There have subsequently been many international studies that have used the same ideas, confirming the importance of his work. Sand eroded from the beach face is deposited offshore, just beyond where the waves start breaking. Over time, most of this sand is gradually moved back onshore during periods of smaller waves. This pro- cess can take up to two years at Durban. In addition to short-term shoreline erosion, coastlines are also subject to a continuous alongshore transport of sand that arises due to the direction in which waves arrive at the coastline. Durban has a predominantly northward sand transport that interacts with the Durban Port’s southern breakwater. The southern breakwater blocks sediment from moving up the coast, resulting in the build up of sand at the south side of this breakwater. If this sand is not transferred to the area north of the harbour, the beaches there will slowly erode. A sand bypassing scheme operates in Durban to prevent this, but relies on the availability of dredging services for implementation. Waves can come from many directions, and the alongshore current can therefore occasionally reverse direction. Of greater concern over the long term is the global problem of an overall reduction in the supply of sand to beaches due to sand mining operations and the building of dams that trap river sand before it reaches the coast. About 80% of all beach sand comes from rivers. Sea level rise due to climate change will also have significant long-term impacts on the stability of our beaches. The research at the Environmental Fluid Mechanics Lab is therefore focused on understanding the dynamic and systemic relationships between diverse causal fac- tors of shoreline change.  Sea level rise due to climate change will also have significant long terms impacts on the stability of our beaches Thermal Integrity Profiler (TIP ™ ) • Evaluates concrete quality inside and outside the reinforcing cage • Accelerates construction with tests conducted during concrete curing • Reveals necking or inclusions, bulges, variations in concrete cover, shape of shaft and cage alignment To learn more about TIP ™ , visit www.pile.com. TIP-Reporter Software