Dredging Dunes Poster
To check out a higher resolution version of the Dredging Dunes poster, click here!
This project capitalizes on two main issues in the Fraser River Delta: 1) the vulnerability of the current coast protection system, and 2) the large amount of dredged materials generated by the Port Metro Vancouver.
Based on recent reports, 127 km of dikes in the Fraser river delta are not built with sea level rise factored into their designs (Sea Level Rise Adaptation Primer, 2013). The cost of dike improvements over the next 90 to 100 years would be nearly $10 billion (Cost of Adaptation - Sea Dikes & Alternative Strategies, 2012). Annual dredging volumes by the Port Metro Vancouver are approximately 3.3 million cubic metres. Ongoing port expansions and deepening of the Fraser River navigation channel by another 2 metres would substantially increase the amount of dredged materials.
Dredging Dunes proposes to link these two issues by first, treating dredged materials in two large management facilities, and consequently transporting the reclaimed sand to create artificial dunes along Vancouver's coast. After the dunes have been constructed, community members become active agents in planting dune vegetation to restore and create habitats. Moreover, the dunes allow for diverse recreational and educational programs to unfold over time.
The proposal combines sustainably recycling a commodity with potential value (dredge materials), with environmental remediation and coastal nourishment. Annually, the project generates enough materials to allow for approximately 8-10 linear kilometres of dune restoration with an average height of 9 metres.
Materials dredged from the Fraser River will be analyzed and separated based on their composition (sand, gravel and clay) as well as the contamination levels. Clean materials can be directly used for dune restoration, whereas contaminated materials will be taken to two new state-of-the-art management facilities to be processed and recycled.
The dunes are constructed with various shapes, slopes and dimensions as well as considerations to wind direction, wave exposure and ecosystem establishment. After mechanical grading, dune-forming fences are installed to reduce wind velocity, thereby causing drift sand to be deposited in the vicinity of the fence. Once fences are covered with sand, cover crops are planted to provide sand surface stability and to protect emerging secondary species. Consequently, a full range of native vegetation that is adapted to local conditions (hind dune, foredune and incipient foredune) is planted to create diverse and sustainable habitats.
A supplemental article from the Vancouver Sun discussing the dredging of the Fraser River. Click here to view.
A supplemental document explaining action to restore dunes at Iona Beach Regional Park along with examples of how this has worked in other areas. Click here to read.
Community participation becomes one of the cornerstones of the project's long-term success. It is critical that communities are intimately involved in the process of designing, implementing and managing appropriate dune restoration strategies that will protect their communities from rising sea levels and the potential devastating effects of extreme tides and storm surges.
Across the Fraser River Delta, the project will establish Dune Restoration Programmes with local communities in order to undertake earthworks to reshape the dunes, replant functional native vegetation, erect fences, design and implement pathways and signage. Another aspect of the project involves community awareness and education. As such, Dredging Dunes can be linked to local schools and other educational programmes to promote stewardship. Financially, using volunteers to maintain these soft infrastructures (dunes and vegetation) is far less costly than typical hard engineering approaches that need replacement every 20 to 40 years.
Dredging Dunes also establishes an ecologically significant and robust coastal landscape, which has the capacity to sustain ongoing development pressures fuelled by population and economic growth. Depending on local needs and circumstances, the dunes will evolve and produce a number of different characteristics (urban dunes, successional dune, washout dune). Beyond their function as protective barriers from flooding, dunes provide critical habitats with high biological diversity due to complex topographic conditions. Moreover, coastal sand ecosystems are important for First Nations as sources of plant resources, or as sites for social gatherings and spiritual activities.
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