Vancouver is currently considering a number of options to strengthen the resilience of the city’s flood defences ranging between $300 million to $800 million.

A number of low-lying areas in the Canadian city, which is bordered by bays and rivers, are at significant and growing risk of flooding from rising sea levels.

Proposals presented to the city Council last week include adapting existing buildings and streets to withstand future floods and building taller seawalls, new dikes and a storm surge barrier.

Tamsin Mills, Senior Sustainability Specialist at the City of Vancouver and author of the city’s climate change adaptation strategy told the Council:

“Based on today’s projections of sea level rise, we have timelines of when we need to start prioritizing different areas and incorporating that lag time into construction time and decision making. When the nuisance flooding becomes intolerable and the fine line, we tip over to wanting that piece of infrastructure.”

The options presented to the Council include proposals which have looked at storm surge barriers in other cities, including Rotterdam and New York.

The city is now seeking to complete a coastal flood risk assessment and develop a city-wide sea level rise response plan.

False Creek - one option alone could cost up to $800m to build and $9.5m per year to maintain

In one scenario for False Creek, an inlet that separates downtown from the rest of the city, and the False Creek Flats, a sea gate would be built under a bridge spanning the creek. The gate, which would protect properties in the inner harbour would be closed several days a year at first, with the expectation that it would be closed increasingly often as sea levels rise. The scheme would cost between $500 million and $800 million to build and $9.5 million annually to maintain.

An alternative option of raising an existing seawall by 2.3 metres would cost between $300 million and $400 million to build and $4 million per annum to maintain.

Image: False Creek option 3 - adapt with planning tools

Another scenario proposes adapting the region via a series of smaller interventions at a combined upfront cost of around $338 million, with ongoing annual maintenance costs of $500,000 as opposed to a major infrastructure solution. Suggested measures  include:

• converting ground level residential spaces to commercial use
• flood proofing ground level windows
• constructing deployable flood shields and temporary stairs for city streets
• fitting  individual buildings with their own floodgates.

Vancouver proactively plans for sea level rise over the next century

Vancouver is proactively planning for sea level rise over the next century, taking the view that doing nothing is not an option.  It also has significant cost implications - a study released earlier this year concluded that flood scenarios on the Fraser River and coastal areas would trigger the most costly natural disaster in Canadian history if no proactive measures are taken. Estimated costs are put at between $19.3 billion and $32.7 billion in direct losses.

Commenting on the issue, Vancouver’s Mayor Gregor Robertson said:

"The massive costs and damages to Vancouver resulting from climate change and sea level rise can't be ignored. Sitting on the sidelines is not an option while climate change threatens our future."

“By taking action today to protect our land, environment, people's homes, and our iconic landmarks from climate change impacts, we're making our city more resilient and saving billions of dollars in the long run."

Interestingly the report also quotes Mark Carney, current Governor of the Bank of England, as saying:

“Once climate change becomes a defining issue for financial stability, it may already be too late.”

Sea level rise in Vancouver related to climate change

The City of Vancouver has been planning and preparing for the impacts of sea level rise across the city over the last few years and partnered with multiple stakeholders to commission a two-part Coastal Flood Risk Assessment to understand the impacts and potential solutions. The first report was completed in 2014 and identified flood hazards, vulnerabilities,  and consequences expected over the next century, and led to a new floodplain map with new flood construction levels.

The second report was completed earlier this year and identified possible options for responding to coastal flood risk in eleven distinct areas of Vancouver's coastline.

According to the City Council, while the flood risk today and in the short term is limited to a few areas of the city, the flood risk increases through time as sea level rise is added to the equation. In 2017, the Council plans to begin engaging with neighbourhoods that will be the most impacted by sea level rise in the near future to identify the best adaptation options.

Response options originated from international examples, literature, and expert opinion on what could be done in the Vancouver context and generally fall into three categories:

• Protect land from flooding via green infrastructure, flood walls, tide gates, dikes, and so on
• Adapt to new flood realities by raising buildings and infrastructure, changing construction practices, and implementing temporary barriers
• Retreat by removing people and infrastructure over time from areas exposed to flood risk

Potential funding could include city-wide fees or levies

The options presented to the Council also examined a number of financial considerations and potential funding sources, including  federal and provincial Government funding, together with regional and local contributions.

Potential sources of regional  and local contributions flagged up to the Council included:

• Regional / local development cost charges
• Local Improvement Tax
• New area specific or city-wide fees or levies

Vancouver belongs to 100 Resilient Cities group

Vancouver belongs to the 100 Resilient Cities group pioneered by the Rockefeller Foundation  which is dedicated to helping cities around the world become more resilient to 21st century physical, social and economic challenges. In the UK Greater Manchester, Glasgow and London also belong to the Group.

100RC supports the adoption and incorporation of a view of resilience that includes not just the shocks—earthquakes, fires, floods, etc.—but also the stresses that weaken the fabric of a city on a day to day or cyclical basis.

Cities in the 100RC network are provided with the resources necessary to develop a roadmap to resilience along four main pathways:

• Financial and logistical guidance for establishing an innovative new position in city government, a Chief Resilience Officer, who will lead the city’s resilience efforts;
• Expert support for development of a robust resilience strategy;
• Access to solutions, service providers, and partners from the private, public and NGO sectors who can help them develop and implement their resilience strategies; and
• Membership of a global network of member cities who can learn from and help each other.

100RC has staff and offices in New York, London, and Singapore to support the work in cities across regions.

Click here to download the Vancouver City Council presentation Preparing for Sea Level Rise - Climate Change Adaptation Strategy Update

Click here to visit the 100 Resilient Cities website