Frank Van Nynatten, Chilliwack’s deputy environmental services manager, is located on the banks of the Fraser River, meters from the dam that protects the city from flooding. DARRYL DYCK / The Globe and Mail
When rivers flow down their banks, the resulting damage is not just the result of nature’s whim. It is also determined by the number of houses, farms, roads and hospitals that people built on the way to a flood.
A new analysis by The Globe and Mail has revealed this Of 150 Canadian communities with a population of more than 10,000, more than 30 have at least a tenth of their buildings on the floodplains of the rivers. This analysis was facilitated by new nationwide flood maps published by the University of Western Ontario.
Highlights Chilliwack, BC: More than 18,000 buildings in this metropolitan area are located on the floodplains of the Fraser and Vedder rivers. This is almost half of all the buildings in the city; no other community we have studied comes close. High River, Alta., Which saw thousands of homes damaged in a 2013 flood, emerged as another community with extensive floodplain development.
Time and time again, construction in floodplains has been exposed as an expensive habit. It can condemn cities to painful cycles of devastation and reconstruction, at great economic and psychological cost to affected residents.
A Globe and Mail Analysis of Flood Models for
the University of Western Ontario proves it
more than 30 communities across Canada have it
at least a tenth of its buildings within the floodplains of the rivers. Chilliwack, BC had an unusually high exposure. The community relies on networks of dikes to protect.
15 CITIES WITH THE HIGHEST PROPORTION
OF BUILDINGS IN THE 100 YEAR OLD FLOOD FLOOD
Buildings in 100 years
floodplain
Boundary of the census metropolitan area
MURAT YÜKSELIR / THE BALLOON AND THE MAIL, SOURCE: TILEZEN; OPENSTREETMAP COLLABORATORS; CANADIAN STATISTICS; MICROSOFT; UNIVERSITY OF WESTERN ONTARIO
A Globe and Mail analysis of flood models by the
The University of Western Ontario shows that more than 30 communities across Canada have at least a tenth
its buildings within the floodplains of the rivers. Chilliwack, BC
had an unusually high exposure. The community relies on networks of dikes to protect.
15 CITIES WITH THE HIGHEST PROPORTION OF BUILDINGS
ON THE 100-YEAR-OLD FLOOD PLAN
Buildings on the 100-year-old floodplain
Boundary of the census metropolitan area
MURAT YÜKSELIR / THE BALLOON AND THE MAIL, SOURCE: TILEZEN; OPENSTREETMAP COLLABORATORS; CANADIAN STATISTICS; MICROSOFT; UNIVERSITY OF WESTERN ONTARIO
A Globe and Mail flood model analysis by the University of Western Ontario shows that more than 30 communities across Canada have at least a tenth of their buildings on floodplains. Chilliwack, BC had an unusually high exposure. The community relies on networks of dikes to protect.
15 CITIES WITH THE HIGHEST PROPORTION OF BUILDINGS ON THE 100-YEAR FLOOD PLAN
Boundary of the census metropolitan area
Buildings on the 100-year-old floodplain
MURAT YÜKSELIR / THE BALLOON AND THE MAIL, SOURCE: TILEZEN; OPENSTREETMAP COLLABORATORS; CANADIAN STATISTICS; MICROSOFT; UNIVERSITY OF WESTERN ONTARIO
This was spectacularly demonstrated west of Chilliwack, in the Sumas prairie, a well-known floodplain flooded last November after a dike breach. The federal government and British Columbia expect to incur $ 3.9 billion in recovery costs due to the November floods, almost all of which will eventually be paid by federal taxpayers. This is the largest disaster recovery charge in Canadian history, and adds to what homeowners, farmers, businesses and municipalities have to pay out of pocket.
Additional public funds are sometimes spent on massive flood protection works to protect vulnerable neighborhoods after the events. The federal government is also considering a program to facilitate the relocation of homes and businesses from high-risk areas, which could require even more public spending.
However, despite the official policies of multiple layers of government seeking to restrict the development of floodplains, some cities continue to allow it. Meanwhile, as the Earth’s climate warms, the footprints of many floodplains are expected to widen.
How to defend or abandon these positions could become an increasingly urgent dilemma for all levels of government, as well as the question of who should pay when previous permits lead to tragedy.
Gaps in the armor
The flood maps of the city of Chilliwack largely corroborate those of the University of Western Ontario. In fact, a 2007 municipal map represents a substantially larger floodplain, mainly because the Chilliwack maps represent a more severe flood than the Western one. But there is a crucial difference: the municipal map classifies most of the floodplain as “protected.”
This is a reference to the 50 kilometers of dikes that surround the city, which are defended by tens of thousands of residents, companies, water lines, railways, the Trans-Canada Highway and a hospital.
Chilliwack’s official community plan only discourages development in a handful of areas considered “unprotected.” It is part of a pattern seen in cities across the country: dikes attract more development and therefore increase exposure to floodplains.DARRYL DYCK / The Globe and Mail
Diking began as early as the 1860s, when settlers flooded the area. The impetus for the construction and improvement of more dikes was provided by the great floods of the Fraser River in 1894 and 1948, and in 1975 of the Vedder River.
Those dikes provided reassurance that they were crucial to Chilliwack’s growth. The development originated on the north side of the present-day Trans-Canada Highway, but extended southward to include the ancient communities of Sardis and Vedder and the surrounding slopes.
Recently, Chilliwack has been one of the fastest growing cities in Canada, its population increased by 12% in the 2021 census compared to 2016. Now the total exceeds 113,000, and city officials expect continued growth in the coming decades.
Daryl Moniz, a real estate agent and chair of the Chilliwack and District Real Estate Board, said affordability is pushing homebuyers in Chilliwack. “They want the single-family home with the dream of the white fence for their family, unlike condominium living which is the reality for many first time home buyers in the Vancouver area,” he said.
Finding space for this growth, however, is a challenge. Chilliwack is surrounded by agricultural land protected by the province and the neighboring first nations. The demand for many thousands of new homes led to the intensification of existing neighborhoods at the bottom of the valley, as well as some development on the nearby slopes.
Chilliwack’s official community plan only discourages development in a handful of areas considered “unprotected.” It is part of a pattern observed in cities across the country: dikes attract more development and therefore increase exposure to floodplains.
DARRYL DYCK / The Globe and Mail
Upstairs, new two-story homes are under construction in Chilliwack this month. Below, a house in the Yarrow neighborhood of Chiilwack is flooded in November 2021.JESSE WINTER / Reuters
At Chilliwack, Mr. Moniz, the floodplain is a “minor or irrelevant” consideration in real estate transactions. “It’s just a way of life, more or less, west of BC”
The problem is that flood defenses can fail and their maintenance is often neglected.
The Chilliwack story proves the point. As severe flooding conditions developed in 1948, locals in the east of the city realized late that their dikes had to be raised. According to a contemporary story, “they put their own trucks into service, turned a 10-acre pasture into a gravel pit and formed the core of an army of 3,500 men.”
These last-minute efforts saved Chilliwack and its environs from complete flooding. However, the dikes failed and flooded several neighborhoods, most notably the Mennonite community of Greendale, Sumas Prairie, west of Chilliwack, which became a 34-foot-deep lake.
“After Greendale’s break,” Chilliwack said, “he took stock of his own defenses and found them missing.”
And not for the last time. A 2015 assessment released by BC’s Ministry of Forests, Lands and Natural Resources noted that many dikes around Chilliwack were “currently too low,” or had other deficiencies.
People are running and walking on the North Arm Fraser River Dam in Vancouver on Friday, April 22, 2022. Darryl Dyck / The Globe and MailDARRYL DYCK / The Globe and Mail
Work has continued over the last decade to improve the dikes, starting east of Chilliwack and moving downstream along the Fraser River. Officials told The Globe that the work could take a decade or more to complete and depends in part on available federal and provincial funding.
Officials are well aware of what is at stake. A 2009 study by engineering firm BGC Engineering estimated the potential damage from a $ 1 billion flood. “The consequences of a breach of the city’s flood protection system would be far-reaching,” a 2016 municipal report said. expensive.
“We don’t start with a blank page, and we have to work with the City Council as it was developed in years …