Sea change
From raising dikes to ‘retreating’ from flood-threatened land, low-lying communities face costly and uncertain future due to climate change
As ocean levels are predicted to rise one metre by century’s end, what is being done to prevent flooding chaos across the Lower Mainland?
Over the next century, Vancouver’s greatest asset could become its worst enemy.
A new climate change report lists the city among the world’s most at risk for losses from rising sea levels and flooding, ranking it 11th after cities such as New York, New Orleans and Mumbai.
“We’re at the point where this can’t be ignored,” B.C. geoscientist John Clague told the Sunday Province. “The only good news is that there is time.”
The report by the Organization for Economic Co-operation and Development was published Tuesday in the journal Nature Climate Change.
Scientists examined 136 of the largest coastal cities in the world and concluded that, without adaptation, total annual losses from flooding could top $1 trillion by 2100.
While the report listed Vancouver among the 20 most at-risk cities in the world based on its amount of “exposed assets,” it did not make the list when defence measures were taken into account. On that list, cities in developing countries took the top spots.
But that doesn’t mean Vancouver and surrounding cities can rest easy, said Clague, a professor at Simon Fraser University.
Local research suggests that as glaciers melt and the oceans warm, B.C. coastal waters could rise one metre over the next century.
That’s enough to overtop dikes, as extreme weather — high tides, strong winds and torrential rainfall in winter, or hot weather that melts mountain snow rapidly in spring — becomes more common due to climate change.
“We’re at the point where this can’t be ignored. The only good news is that there is time.”
— JOHN CLAGUE
GEOSCIENTIST, SFU
In December, a report released by the provincial Ministry of Forests estimated dike improvements over the next 90 to 100 years could cost $9.5 billion.
“Who’s going to pay for that?” asked Clague. “Municipalities don’t have that kind of money.”
‘Managed retreat’
If municipalities will struggle to find money to upgrade flood protection, Stan Van Keulen doesn’t have a hope.
The longtime Surrey dairy farmer and president of the Mud Bay diking district has a small annual budget to maintain the dikes along the Serpentine and Nicomekl rivers in a 1,110-acre area crossed by Highway 99 and the Burlington Northern Railway. The tracks serve as the sea dike.
The district runs a taxation program among landowners to supplement funds received from the City of Surrey for dike maintenance. For capital projects, Van Keulen must “beg and borrow” to get the money he needs. He’s been turned down many times.
The days between Christmas and New Year find the farmer patrolling the dikes during the winter’s highest tides. Twice in the last 40 years, Van Keulen’s land has been flooded, once when a dike broke and another when a storm surge overtopped it for about 30 minutes. Both times, the damage was extensive. Salt water ruined crops and the impacts were felt for at least three years after.
In normal years, however, the land is extremely productive.
So it was a surprise when Van Keulen learned the Mud Bay area was a place where “retreat” — buying out landowners and leaving the area to the sea — might be considered a better option than raising dikes.
The idea is contained in the Ministry of Forests report, which was prepared by a consulting firm and examined various options for protecting Metro Vancouver’s shoreline reaches.
In all communities except Mud Bay, dike widening, breakwaters or flood proofing were considered better options than retreat.
For example, in West Vancouver, dike construction was recommended to protect older homes near Ambleside. The report said that in Kitsilano, a small dike would be the best option to protect lower areas, while in Crescent Beach the existing dike would need to be raised by about three metres. The report indicates dike widening may cost the same amount as buying out Mud Bay landowners, but it recommends “managed retreat” instead.
The blow is softened, however, with a caveat that retreat may not be reflective of the city’s wishes.
Surrey utilities manager Jeff Arason agreed it is not the city’s preference, adding that “by no means is the city actually endorsing retreat.”
Still, Van Keulen said “the very notion” is disturbing. He believes a seawall dike across the bay from White Rock to Tsawwassen would protect the entire area from flooding, although he realizes there would likely be environmental concerns with such a project.
Challenges in defence
Environmental impact is one of many issues that must be dealt with as governments move to mitigate flood risk. In order to increase the height of a dike, its base must also be widened, impacting sensitive environmental areas.
A City of Surrey report from 2011 questions whether Fisheries Canada and the provincial Ministry of Environment will relax guidelines for dike work.
There are also issues when seawalls front homes and there is little room to widen them.
The Surrey report highlights other concerns too: The flood construction level, the required elevation for the floors of new homes, would need to be raised as much as 4.5 metres in some places. Older homes in lowlying areas could face problems with drainage, requiring improvements to sewage and water systems.
The Ministry of Forests report also notes difficulties moving forward. For example, dike elevation near Vancouver International Airport would result in the need to rebuild some maintenance roads since locating them on higher dikes would obstruct air traffic.
But while the challenges are many, there’s also plenty of optimism that Metro Vancouver will rise to the threats presented by rising water.
City flood strategies
Delta Mayor Lois Jackson remembers sitting in on a climate change workshop at a conference in Ottawa in 1999. It was her first year as mayor and she returned home filled with new ideas.
“I was roasted in the press for taking this wild and weird stance,” she recalled with a chuckle.
In the decade since, climate change has become a major issue for Delta, and one that Jackson feels the city is “ahead on.”
Delta deputy director of engineering Hugh Fraser said the city has a strategy for dealing with climate change, although it is “not all written down yet.”
But that hasn’t stopped council from moving ahead with studies, as well as establishing new protocols. Part of that has meant preventing new development in some areas, while requiring developers to raise
“I was roasted in the press for taking this wild and weird stance (on climate change).” Delta Mayor Lois Jackson, who says her city is now ahead of the game in terms
of climate change preparation
dikes as part of their work.
Delta has also benefitted from a University of B.C. study by Dr. David Flanders, who produced computer visualizations of rising sea levels, illustrating the ways water will impact communities and modelling various flood protection scenarios.
“To me, the visualizations are the only way that you can tell the complete story of climate change and its impacts in a low-lying coastal community,” he said in a news release about the project.
“In other words, seeing really is believing in this case.”
In Richmond, the climate change plan is fully integrated into a detailed flood management strategy with budgeting for capital projects, said engineering director John Irving.
“This is a very manageable issue for us,” he said. “To raise our dikes . . . will be a $200-300 million job, but when you think that it will protect billions of dollars in assets, and that we need to achieve that rise over decades, it’s very do-able.”
In Surrey, a climate change adaptation strategy will come before council in the fall, said Arason.
Vancouver, too, has a strategy, and bills itself as the first Canadian city to create one.
All Metro Vancouver municipalities have representatives on the Joint Program Committee on Flood Hazard Management, a board chaired by the Fraser Basin Council. The provincial government, First Nations and private sector stakeholders are also represented.
FBC executive director David Marshall said the council has been successful at securing federal funding for various scientific studies that can be used by all groups. They are in the process of working out a strategy for the future. “I’m quite optimistic,” he said. FBC senior manager Jim Vanderwal said there are “tough conversations” that need to be had, especially around the subject of retreat and land purchases for dike improvements, but municipalities seem to be prepared to have them.
Provincial inspector of dikes Neil Peters said in an email that while the work can be spread over several decades, it is “crucial to complete technical studies and start planning now.”