Effects of topography on wind flow and sand transport & development options - Ocean Beach Domain Technical Report
- Author
- Pattanopol, W.; Hilton, M.J.; Wakes, S.J.
- Year
- 2011
- Publisher / Organisation
- Dunedin City Council
- Summary
- The Ocean Beach Domain in Dunedin, New Zealand has an ongoing issue with persistent scarping leading to high maintenance, poor public access, and potential hazards due to the infill used to create the foredune. The ongoing cost of replacing sand and repairing erosion damage has led the local council to explore the possibility of a more sustainable long-term solution. A foredune will still be required but the question is how much space between the beach and foredune is needed to alleviate the current issues. Computational Fluid Dynamics modeling has therefore been used to identify suitable future foredune morphologies in this situation. The scenarios modelled were; the current unfeasible Marram grass covered steep foredune system; the relatively untouched (1890) morphology; and interim positions that accommodate the coastal processes by retreating the foredune system. Additional three-dimensional simulations using LIDAR data to recreate the topography give a relationship between the dune system and the dominant direction of the wind flow. The success of these proposed dune morphologies is discussed in terms of sand transportation, fit to the council's ongoing management goals which includes protection of low lying houses and an analysis of the success of using such numerical simulation in coastal planning. Numerical simulation is shown to present the opportunity to help with future coastal management scenarios. This work has shown that the current dune morphology at the Ocean Beach Domain is unrealistic but that there are alternative profiles that could satisfy both public and council imperatives.