Perforated edge: Reconnecting Coastal Cities to the Water

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Perforated Edge demonstrates a model of flood-adapted urban development that uses multiple strategies (e.g. elevated grades, flood gate, new water channels, wetlands) to safely bring water into the city for ecological enhancements, recreational opportunities, and waterfront development. Through these measures sea level rise becomes an opportunity for coastal communities to increase their livability, ecological richness, and resilience.

overview of the idea

Rapid sea level rise is presenting a serious challenge to the future of our coastal cities. Conventional flood protection infrastructure, such as dykes, create a disconnect between our communities and their waterfronts. This results in lost opportunities to experience the water, lost recreational spaces, and lost intertidal ecosystems. At the same time, many coastal cities are wanting to revitalize their urban waterfronts but are challenged to find ways of safely connecting people to the water.

This project seeks to show how Richmond, as a representative coastal city, can adapt to sea level rise while reconnecting the city and landscape to the water. This proposal demonstrates a model of flood-adapted urban development that uses elevated grades, a flood gate, and new water channels to safely integrate water with the urban fabric while protecting against floods and sea level rise. 

At the heart of this proposal is a 13 hectare tidal channel park that brings the Fraser River into the heart of Richmond’s City Centre, reconnecting people with the water along 3 kilometers of new riverfront property. The tidal channel park also allows landward wetland migration, supports juvenile salmon rearing, and filters urban stormwater runoff. 


how it works

This proposal will give coastal cities greater protection from sea level rise without cutting off their important connection to the surrounding ocean or rivers. The proposal uses a combination of structural and ecological elements, illustrated in the accompanying diagrams.

(1) Space for new intertidal habitat is created by shifting the primary dyke inland. This will help mitigate the loss of coastal wetlands due to “coastal squeeze.”

(2) A primary dyke is maintained along the coastline for protection from high water levels. The height of the dyke would be determined by sea-level projections with consideration for storm surges, wave run-up, land subsidence and appropriate safety factors.

(3) A secondary dyke (“superdyke”) is created inland from the primary dyke. The secondary dyke allows water to be brought into the urban fabric under normal water levels. Underground parking and rainwater storage can occur under the dyke.

(4) The mouth of the channel has a flood gate that closes during high water levels. 

(5) Between the primary and secondary dykes is a new water channel. The channel and adjacent lands generates tremendous opportunity for new waterfront development, public recreational space, and diverse coastal ecosystems that would otherwise be lost due to sea level rise.

(6) Terraces and “benches” within the water channel create space for new intertidal wetlands to support coastal vegetation and wildlife species, including juvenile salmon.

(7) Tidal swales bring water from the channel into the surrounding city fabric, helping reinforce the coastal identity of the community

IMAGES AND VISUALIZATIONS

Poster Board

See a higher resolution poster featuring images from the gallery above. Download.

How communities will adapt and thrive

Sea level rise is an enormous challenge to coastal communities, but it also presents an opportunity. This proposal uses structural and ecological strategies to help coastal communities safeguard their lands against sea-level rise, while having the opportunity to gain the additional benefits of new waterfront development, expanded intertidal wetland habitat, and an experientially-diverse public realm.

From a social perspective, improved connections to the water make the waterfront accessible to a broader cross section of society, and not just those who can afford waterfront real estate. The public space associated with the water channel and adjacent uplands creates room for a range of community amenities, such as a community centre, market plaza, recreation, play, and social space.

Economic opportunities are created through the creation of new, accessible, waterfront lands. While large-scale projects like this cost more than basic flood protection measures (e.g. upgraded dykes), this proposal yields many more benefits, including increased economic development associated with waterfront revitalization.

Environmental benefits of this proposal include new intertidal wetland habitat to support a diversity of species (including juvenile salmon) and the creation of a complete walkable neighbourhood that has a lower carbon footprint. 

This combination of flood-adaptation measures will allow coastal communities to adapt to rising sea-levels while increasing their livability, ecological richness, and identities.

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