MULTIPLE USE PLANNING OF THE SUMNER COASTLINE K. ANDERSON, R. COOPER, A. EAVES, R. ELLEY, S. KILKENNY-BROWN. 1 TABLE OF CONTENTS 1. Executive Summary Page 3 2. Introduction Page 4 3. Proposals Page 7 3.1. Dune Restoration Page 7 3.2. Creation of High Tide Beach Page 8 3.3. Artificial Reef Page 9 3.4. Tidal Power Generation Page 10 3.5. Shag Rock Monument Page 11 4. Methods Page 13 5. Results Page 14 5.1. Questionnaire Results Page 14 5.2. Focus Group Results Page 19 5.3. Interview Results Page 20 6. Discussion Page 22 6.1. Key Findings Page 22 6.2. Limitations and Recommendations Page 24 7. Conclusion Page 26 8. Acknowledgements Page 27 9. References Page 28 10. Appendices Page 29 Appendix A: Results Tables Page 29 Appendix B: Questionnaire Comments Page 32 Appendix C: Focus Group Key Points Page 34 Appendix D: Interview Key Points Page 36 2 1. EXECUTIVE SUMMARY The purpose of this research report is to identify the possible development proposals for the Sumner coastline post earthquake, whilst working with the Sumner community. Five proposals were selected to investigate; • Dune Restoration • Artificial Reef • Tidal Power Generation • Creation of a High Tide Beach • Shag Rock Monument A multipurpose cycle/walkway and salt baths were also popular suggestions from the community towards the future development of the Sumner coastline. Research methods that were used consist of a combination of; • Web site development • Questionnaire • Focus groups • Interview In general the combination of research methods complemented each other as they allowed for progressive forms of data to be collected and tabulated in a clear concise order. Key Findings: Dune restoration and the development of a high tide beach were the most popular options for future developments. Tidal power generation and a monument at shag rock were the least popular options. Perception of the current management of the coastline is mixed, although marginally unsatisfactory to poor. The most common activities experienced in the Sumner coastal zone according to our survey were walking, surfing, swimming, running and barbeques/picnics. A joint walkway from Scarborough to Redcliffs was supported by a large majority of the community. Research limitations: • Conflicting interests • Cost • Lack of coastal science to support developments • Uncertainty on true community aims 3 2. INTRODUCTION The aim of this report is to discover the different coastal development options for the Sumner coastline. We have worked with the Sumner community group to create five possible development proposals, and have investigated each option to find the most suitable proposal for Sumner. The five proposals were dune restoration, building of an artificial reef, creating tidal power generation, construction of a high tide beach, and creation of a Shag Rock monument. The suggestion of a joint cycle/walkway along the coastline from Scarborough to Redcliffs was seen to be a strongly favoured idea that would benefit recreational users along the coastline. The creation of salt water baths was another popular option that would require further research. Our group used several methods to collect data; the development of a website outlining our research, questionnaires which gave the public opinion of the development options, the use of focus groups, and a personal interview. Figures 1, 2 and 3 below illustrate the study area and the location of the five outlined proposals. 4 Figure 1: Map of the location of Sumner beach in the New Zealand context Figure 2: Birds eye view of the Sumner coastal zone 5 Figure 3: This shows a 3D image of the Sumner coastline area. It is illustrated with the different development proposals 6 3. PROPOSALS 3.1 DUNE RESTORATION Dune management on the Sumner coastline has been irregular over the past, however after the Christchurch earthquakes the community has raised concerns over the management and sustainably of the dune systems and the protection they provide to the urban development, which is located directly behind the dunes. The report “Community-based Dune Management for the Mitigation of Coastal Hazards and Climate Change Effects: A Guide for Local Authorities” provides an adaptive approach to mitigate the effects of sea level rise while raising the communities awareness of coastal hazards. “Performance of the indigenous sand-binders planted on a reshaped Foredune at Okakura Beach, New Plymouth” aims to determine whether replanting indigenous sand-binders is sufficient to stabilize the dunes and protect the scenic reserve behind the foredune. These two reports have provided essential information in regards to the Sumner coastline and the possible future redevelopments of the dune systems. Figure 4: Dune restoration quadrants on Sumner Beach The combination of data collection and support from the literature illustrates the strengths community dune restoration would have on the Sumner coastline. The 7 development would allow for present and future protection for the underlying threat of sea level rise and flooding. The redevelopment could also influence the increase of native biodiversity along the coastline. Management of the dune systems would ideally be by the community so that there is invested interest in what happens in the future. These practices are already in place in five quadrants located north of cave rock (Figure 4). The problems experienced when redeveloping the dune systems include cost and also community support. This proposal would require volunteers‟ work in order for it to be successful. 3.2 HIGH TIDE BEACH ALONG THE SCARBOROUGH ESPLANADE The implementation of a sand nourishment and revegetation program is the first step in creating a high tide beach. Introduction of native plants such as Spinifex and Pingao would create the greatest natural amenity value. The cost and return period of sediment nourishment is of great consideration here. Secondly, an extension of the breakwater adjacent to the slipway is needed in order to trap sediment losses due to longshore drift. Material for this extension can be sourced from the rocks created by the collapsing cliffs surrounding Sumner post the February earthquake. The implementation of these plans will directly alter the wave angle of approach, the effects of storm surge and spring tides. Further consultation, modelling and measurement will be required to assess the effects on the dynamics of the coastal geomorphology to ascertain the feasibility of this proposal. All considerations need to comply with the New Zealand Coastal Policy Statement 2010. There are two main literary items investigated to ascertain the feasibility of a high tide beach at the Sumner esplanade; a study by van Vuren et al. (2004) using numerical modelling to predict future cost benefit analysis for approaches to coastal defence and, the creation of an inventory of facilities and user recreation data, for which coastal managers can base their planning has been under taken by O'Mahony et al. (2009). Van Vuren et al. (2004) established through the means of iterations in a Monte Carlo simulation the future sediment nourishment return period required and economic viability for various predicted shoreline profiles. They address the rationale that 8 climate change will cause sea level rise affecting Holland's particularly low lying hinterland. In natural landscape environs, the coast would be allowed to recede at a minimal cost to society. Coastal defence in built up areas was assessed as to whether the economic cost of protection outweighed the capital and infrastructure in the zone. Allowances were also made for any future economic expansion of the contentious zone. This type of cost benefit analysis is very beneficial to the planners and policy makers to future scenarios of coastal geomorphology and societal influence. The second review of marine policy regards spatial planning for Cork Harbour, Ireland, by (O'Mahony et al. 2009) claims that in order for objective planning of the coastal environment to be achieved, accurate spatial data on recreational use and interactions needs to be gathered. This allows for equitable fair future development. Both research articles have benefits to the assessment of the creation of a high tide beach at Scarborough. O'Mahony et al. (2009) illustrates good methodology to assess public opinion for such a scheme and the implementation of an integrated planning and management structure in order to avoid conflicts. Van Vuren et al. (2004) provide the tools for an accurate feasibility assessment, allowing the dynamism of coastal geomorphology to be estimated and economic projections calculated. 3.3 ARTIFICAL REEF DEVELOPMENT An artificial reef is an underwater structure man-made for one or a combination of three rationales: 1) Aiding ailing ocean ecologies by giving sea flora and fauna a home and feeding ground 2) Protecting coastlines from erosion 3) Creating or improving the quality of surf for sport and recreation. A combination of all three of these reasons could bring benefits to the Sumner coast in many ways. Many reefs are built using objects that were built for other purposes, for example by sinking oil rigs, wrecked ships, or by deploying rubble or construction debris. Other artificial reefs are purpose built from PVC or concrete. It has been suggested that the use of damaged construction material and loose rubble from landslides from the Canterbury earthquakes could be used as a more cost effective way to construct an artificial reef. Concerns over pollution and cultural factors may be 9 in opposition to this use. Development of an artificial reef can have its drawbacks, initial and ongoing costs of development can be very high in comparison to other suggested proposals. The natural sedimentology of the coastline can also be altered dramatically with unknown consequences to local and wider coastal environments. The perceived benefits from the construction of an artificial reef are also unknown until after its development, therefore a large amount of money may be spent on an option with little benefit to the community.