November 29, 2021

Flooding, Sponge Cities, Resiliency, & the Need for Regional Response

Everything old is new again~and streams and old river beds have a renewed purpose in weatherproofing  and providing new recreational spaces in  spongy cities.

It is certainly time to redefine resiliency, sustainability and climate change as not only reactive but proactive. The concept of blueways and new ways to allow water to slowly perk into soils, and to make surfaces permeable is needed.

In the weekend Vancouver Sun,  one of the letters to the editor was from an individual who was originally from the Netherlands. They pointed out that the Netherlands has for centuries dealt with water, and after a disastrous deadly flood had completely overhauled their water management system, since that country was largely below sea level. They suggested that Sumas Prairie be renamed Sumas Polder, as it was originally a shallow lake with First Nations use and significance that had been drained and diked for farming early in the 20th century.

A “polder” is defined as “a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are: Land reclaimed from a body of water, such as a lake or the seabed. Flood plains separated from the sea or river by a dike.”

There are over 3,000 polders in The Netherlands, and half of that country’s land has been reclaimed from the sea.

The  sponge city concept incorporates ancient watersheds and streams into city and rural landscapes. Metro Vancouver is situated on a river delta, and Vancouver is riddled with underground streams, many hidden in development~and there is a treasure trove of materials available at the University of British Columbia that hint at the complexity of the natural stream beds.

In reacting to climate change and the extreme weather, estimates are now being made at what it will cost to raise dikes for sea rise and dramatic rain events: Richmond estimates the cost at one billion dollars, and Delta’s initial estimate is at 660 million dollars.

This article by Gordon Hoekstra in the Vancouver Sun discovered the price of reinforcing and adding to the 400 kilometres of dikes for fifteen metro Vancouver communities (plus Squamish) exceeded 3 billion dollars.

It is a sobering amount and it is reactive not to the old fear of Fraser River rise because of snow melt, but  to intense rainstorms  increasing in frequency due to global warming.

This requires co-ordination not just in keeping water out in severe storm events, but finding ways to capture water and percolate it slowly on city surfaces. Less asphalt capping, more porous site coverages and increased separation of storm and sanitary sewers (which are always deferred in municipal budgets) prevent toxic runoff from flooding and  impacting oceans and watercourses.

This is where regional government with proactive strategies to co-ordinate policies and work across the region can come in.

Currently it is a non-profit organization, the Fraser Basin Council that was charged with creating a flood management strategy which is not yet complete. Given the importance of working together across the region, this role should be re-examined and the work embedded in a regional  structure on sustainability and resiliency, with policies to manage water as well as to dike it out.

Last year the Fraser Basin Council prepared this YouTube video below suggesting what would happen when the next regional flood occurred. The video says that a spring flood is a one in five hundred chance event. No mention of a fall flood, although it does say that climate change is not really factored in to their assessment.

Is it now time to craft a prudent  policy plan within a regional governmental structure for future climatic events?




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  1. I find the description of Vancouver as a ‘sponge city’ interesting. As you no doubt know, the increased presence of huge homes in Southlands (a ‘below-sea-level’ neighbourhood on ditched land on the north arm of the Fraser) requires thousands of tons of sand used as a ‘pre-load’ to push the water out of the soil before building. I’ve often wondered what happens to all that water. Where does it go? And how does pre-loading contribute to an increase in flooding?

  2. The map shown on this older webpage shows the “Regional Growth Concentration Aeas” under the 1996 LRSP – before politics got in the way and low-lying ichmnd insisted on being added. Passage of the Plan required unanimous approval and Richmond has stonewalled the process.
    You can clearly see that the Growth Concentration Areas are on higher bedrock, not in Richmond or Delta.

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