Masters Thesis Abstract: Rei Ishikawa
The Coastal History and Dynamics at Rapahoe Bay , West Coast , New Zealand
The threat of coastal erosion is an ongoing hazard in the West Coast region and is threatening to damage property and infrastructure. One particular area that is under threat from coastal erosion is Rapahoe Bay , a prominent headland bay located 15km north of Greymouth. This research will investigate the coastal history and dynamics in Rapahoe Bay to provide an improved understanding of the coastal processes with in the bay and to predict possible scenarios for the future of this coastline. Four key questions have been created to thoroughly study a variety of aspect about the field area. They are:
- What is the coastal history at Rapahoe Bay ?
- What are the beach types and how do they vary spatially?
- What are the current coastal processes that occur and what do they induce? What are the quantitative figures for these coastal processes?
- What is the prediction for the future at Rapahoe Bay coastline?
A wide range of methods are involved in this research and each of the key questions utilise a different method. The coastal history will be examined comparing aerial photographs dating back to 1938 to map shoreline change. The beach types will be studied using a combination of digital terrain models (DTM) and general observations. The coastal processes will be investigated incorporating 20 year hindcast data and the shallow wave nearshore model (SWAN). The final question combines the results of the previous questions and includes sea level rise and an insight to 'zeta' plan form shape to predict the future of this coastline. The final results will assist the Grey District Council in decision making towards managing coastal hazards in the area.
My research started on the 1st of March and I have completed my proposal, secured funding from the Grey District Council and have visited the field site. I am currently gathering relevant literature and learning to use the DTM equipment required for my field visit. I am also waiting for the aerial photographs to arrive from New Zealand Aerial Mapping. Another field visit is currently being planned with department staff to test the equipment on site.