UBC Undergraduate Research

Soft shoreline alternatives for coastal stabilization and habitat enhancement Russell, Danielle

Abstract

This report attempts to answer the question; How can Port Metro Vancouver incorporate more environmentally sustainable shoreline management strategies? ‘Soft Shorelines’ is the term most often used to describe the practice of sustainable shoreline management. In general, soft shorelines are used in place of traditional ‘hard’ structures (ex. seawalls, groynes, etc.) to stabilize coastlines against erosion while maintaining natural habitats by mimicking natural processes. The following report presents my argument in favour of soft shorelines as they are more environmentally, economically, and socially sustainable then traditional hard structures. By examining North American case studies of what other port authorities and municipalities are currently doing, I have compiled a list of best practices that may guide PMV in future implementation. My research methods included a comprehensive literature review followed by four interviews with local experts on this topic. The interviewees included Dr. John J. Clague, a sea-level rise expert, and Dave Mclean, Derek Ray, and Rowland Atkins, all respected and knowledgable soft shoreline experts. This research led me to understand the basic principles for implementing a soft shoreline: identify source of problem, remove hard structure (if possible, if there is one), replenish shoreline with natural materials and species that have been lost to erosion and what will be lost to erosion until the shoreline is able to be replenished again, and continual habitat monitoring and material replenishment. Each soft shoreline project that I outline in the report is similar but with regional differences as this method of coastal stabilization is case specific. Factors that influence how the shoreline will be protected depend on the water salinity (which influences species that can be incorporated), whether the site is a sediment ‘sink’ or ‘source’, the history of the site (existing hard structure or pollution), whether it is inhabited (by humans or invasive species), and/or how sea-level rise will influence the long-term. Many other aspects must be considered as well including the type and shape of the shoreline which can all be managed by looking to nature to understand the natural forces at work. Throughout this paper I outline many soft shoreline techniques while also emphasizing that all coastal processes must be considered. When we understand what the problem is, whether it is sediment depletion or increased erosion, we can then mimic the natural processes to protect the coastline and habitats rather than try to constrict them. From my research, I have formulated recommendations which are synthesized below that could be included in future policy changes surrounding soft shoreline implementation. Along undeveloped shorelines, stabilization projects using soft techniques that enhance habitat can be achieved with the constant replenishment of sediment and replanting of vegetation to not only improve aquatic and inter-tidal habitats but also to sustain shoreline sediment. Other methods can be implemented alongside replenishment to reduce the frequency that shoreline materials need to be replaced including resloping of the land as well as the placement of off-shore natural breakwaters. A more more gradual slope reduces the waves energy as it breaks on the shoreline and also increases runoff for better drainage which can also be adapted more easily to rising sea level. Additionally, natural off-shore breakwaters such as artificial reefs can be constructed below the surface using boulders, mussel beds, vegetation, or a combination to promote habitat colonization while reducing wave energy. Along already existing hard structures that can not be removed, try to incorporate these soft shoreline techniques where possible.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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