British Columbia

West Vancouver flooding could be sign of worse to come

“Two years ago we had a similar type of problem in North Vancouver, and if you look at all the climate modelling, we’re going to have more extreme events.”

UBC prof says changes, big and small, could make North Shore more resilient to extreme weather

The water flooded parts of the 4400 block of Marine Drive. on the night of June 14, 2016. (Gian-Paolo Mendoza/CBC)

Without changes both big and small, floods on the North Shore, like the one that hit West Vancouver Tuesday night, will only get worse, says University of British Columbia professor Hans Schreier.

Schreier says development, deforestation and climate change are largely to blame for the recurrent floods.

"Two years ago we had a similar type of problem in North Vancouver, and if you look at all the climate modelling, we're going to have more extreme events," he told On The Coast guest host Gloria Macarenko.

"And what we're doing in the urban environment, we make everything impervious: that means the water can no longer infiltrate and as a result it runs over the surface into creeks and then the creeks are no longer able to handle the extra water."

Schreier calls the North Shore a "worst case scenario." The area gets about 2,500 mm of precipitation every year — the airport gets about 1,400 — and heavy urbanization means water can't drain.

UBC professor Hans Schreier says the North Shore is a “worst case scenario” when it comes to flood risks in a changing climate. (CBC)

He says the region is going to need "innovative" storm management solutions going forward.

Some ideas, he says, include building driveways with more pervious materials, or even making grass driveways; creating rain gardens; and more topsoil beneath lawns for water absorption.

But on a larger scale, roads and parking lots need to be thought of, he says, and instead of funneling water into streams and pipes, cities should consider making better use of swale features.

A swale is a low tract of moist or marshy land that can be artificially created to manage water runoff, filter pollutants and increase rainwater infiltration.

At the watershed level, Schreier says governments need to allow river systems to exist more naturally with bigger buffers around them and embrace wetlands in urban environments.

"Wetlands are the best water storage and best water filtration systems," he said. "If we can integrate wetlands into the city, particularly on the North Shore, we can actually do quite a lot to reduce these extreme events."

With files from CBC Radio One's On The Coast

To hear the full story, click the audio labelled: Without changes on the North Shore, flooding will only get worse: prof