The spectrum of coastal structures used to combat erosion at Wainui Beach, Gisborne, New Zealand Conference Paper
- Author
- Dunn, A.; de Lange, W.P.
- Year
- 2003
- Journal / Source
- Coasts and Ports Australasian Conference 2003
- Pages
- 8
- Summary
- Property erosion at Wainui Beach was identified as a problem in the 1900s, leading to the first coastal structures being built in the 1920s for the sole purpose of protecting beachfront property. Individual homeowners privately constructed isolated seawalls from concrete, timber, or stone-filled oil drums. In the 1960s responsibility for coastal protection was accepted by the wider community, with the construction of a groin system along 2.1 km of the beach, and a short log-rail seawall between the southernmost groins. However, isolated private constructions continued to appear. A second public protection scheme – a series of gabion baskets – was assembled in the mid 1970s and coexisted with the groin system into the 1980s. During the 1970s engineers evaluated the existing groins and reported that they were ineffective, leading to the eventual removal of most of the groins in the early 1980s. Subsequently, the 1980s and 1990s only saw the addition of rip-rap at several places along the shoreline. A review of the available data indicates that these structures were all erected in response to foredune or property erosion suffered from large episodic storms, or a sequence of closely-spaced smaller storm events. The magnitude of episodic storm erosion at Wainui is significantly greater than long-term shoreline trends, which could lead to the misinterpretation of future coastal responses. This paper discusses the lessons we have learnt from the history of coastal structures at Wainui Beach and identifies significant knowledge gaps, which have important implications for future long-term solutions