Adelaide’s beaches are the most visited public land in South Australia. The Adelaide’s Living Beaches Strategy has been developed to protect coastal properties and infrastructure, as well as maintaining Adelaide’s metropolitan beaches for the benefit of beach users. The strategy is expected to reduce the cost of managing Adelaide's coastline by about 20%.
The West Beach area has been a particularly erosive part of the Adelaide coast for decades. This erosion has been managed with regular beach replenishment via a backpass pipeline. DHI was commissioned to undertake a numerical modelling of the coastal processes at West Beach to gain greater insight into the nature of the erosion and the effectiveness of possible management options.
Last Tuesday 11 July 2017, the City of Charles Sturt ran a workshop on this modelling with DEWNR and DHI, as well as other key stakeholders. The workshop discussed the analysis by DHI of the survey together with other data and the preliminary modelling that has been completed to date.
The modelling analysis involved the development of a comprehensive coupled MIKE 21 HD and SW model of the Gulf St Vincent to enable an eight-year hindcast of waves, water levels and currents to be developed for the study area. Due to the size of the model domain and the detail of these processes required to understand the erosion processes in the study area, the hindcast simulations were performed on the ‘Raijin’ supercomputing facility at the Australian National University in Canberra. Approximately 50,000 core hours of computational time was used to develop the hindcast using DHI’s software on ‘Raijin’.
The detailed hindcast will be used to drive a MIKE 21 Shoreline Morphological (SM) model of the study area. MIKE 21 SM is DHI’s advanced new model for studying coastal morphology. It enables robust long-term predictions of shoreline evolution for complex shorelines, where inherent two-dimensional features of the bathymetry and coastal structures, significantly influence the shorelines evolution.
An initial assessment of beach volumes indicates that a significant amount of sand is being transported by natural processes from West Beach to Henley Beach. This will be investigated further as part of the modelling programme, as will possible future coastal management options briefly discussed at this workshop.