Stormy with a chance of flooding

Information on future flood risks in the Lower Mainland is plentiful, but it’s only useful if governments act on it



From forest fires and heatwaves to storm surges and heavy rainfalls, British Columbia is constantly battling our changing climate’s weather patterns, and according to experts, we are unprepared for the worst of it.

A report titled Under Water: The Costs of Climate Change for Canada’s Infrastructure released by the Canadian Institute for Climate Choices found that Canada’s infrastructure isn’t prepared to withstand the long-term impacts of climate change.

One of the report’s key findings is that Canada’s warming climate is accelerating the possibility of weather-related damage to some of the country’s most important infrastructure. As sea levels rise and rainfall levels change, “flood damage to homes and buildings could increase fivefold in the next few decades, and by a factor of ten by the end of the century, with costs as high as $13.6 billion annually,” according to the report. This is in addition to the predicted $5.4 billion annual costs for road and railway damages caused by increased temperature and rainfall. 

Dylan Clark, a senior research associate at Climate Choices and one of the authors of the report, says their research provides a picture of how much climate change could cost Canadians and our economy.

“That’s going to cost Canadians billions of dollars unless governments take policy action starting today,” Clark says. 

Proactive investment in infrastructure is the “most cost-effective way to protect the services people, businesses, and the economy depend on,” states the report. However, it notes that not all of the impacts and costs can be quantified, as the loss of services and reliability “will have far-reaching social and economic consequences.” 

“While we focus on economic costs and dollar values, that’s just the tip of the iceberg,” Clark says, adding that there are many other impacts and costs that they’re not able to focus on in their work. 

“That being said, moving forward within this work is providing policymakers and Canadians at large with a better understanding of how climate change could impact all aspects of our lives and communities, unless we take action to reduce greenhouse gas emissions,” Clark says.  


Floods in the Lower Mainland

“B.C., and the Lower Mainland specifically, is among probably the worst and most costly of places for coastal flooding in all of Canada,” Clark says.

There are three kinds of flooding being looked at, and all of them are driven by extreme weather, says Paul Richard, an environmental protection technology instructor at Kwantlen Polytechnic University. Each type of flooding requires different strategies to deal with.

“The first one is a huge volume, like a deluge, of rainfall. And that’s always a possibility engineers talk about, [like the] ‘flood of the century’ or ‘one in every 25 years’ kind of thing.… So what used to be the storm of the century might become the storm coming back every 20 years.”

The second type of flooding is fluvial flooding, or river flooding, which happens when the water level in a river, lake, or stream overflows onto surrounding land. Richard says the chances of the Fraser River overflowing could increase due to heavy rainfall or snow melting quickly upstream.

“Then you have coastal [flooding], which is usually a combination. It could be high tide and a lot of wind pushing extra water towards the coast,” he says.  

Larger amounts of rainfall are usually associated with very low pressure in the atmosphere, which can also contribute to abnormal rises in the water level of the oceans or lakes, otherwise known as storm surges, Richard says. 

“We all know that the atmosphere is getting warmer, and a warmer atmosphere can hold more water,” says Robert Larson, a hydrologist with Ebbwater Consulting, a flood management company. “So that means it has more power to suck up water, there’s more evaporation.”

“Places that are dry are getting drier, and places that are wet are getting wetter as a result of this process,” he adds.  

Larger rainstorms in the fall and winter months can be the result of atmospheric rivers, which are long bands of moisture that carry precipitation from tropical regions, like the Pineapple Express. These rainstorms are driven by temperature gradients that develop between the North Pole and the equator. Larson says that Vancouver is specifically susceptible to these rain patterns because of eastern winds that carry precipitation from Hawaii.

As rainfall patterns change with the climate, protecting infrastructure and vulnerable areas from damage will require more attention to water management.

“Flooding has always generally been seen as an engineering problem. It’s been this idea that water is affecting infrastructure that was built by humans, and therefore the solution is to build ourselves out of the problem, usually in forms of flood defences like dams and dikes,” Larson says. 

“Long-term solutions are not sexy. They involve doing painstaking diligent work to review land-use planning and redefining policy and bylaws to control or at least reassess development patterns.”


What is currently being done to prepare flood risk areas

Metro Vancouver has a regional growth climate strategy called Climate 2050, which integrates climate change preparedness in land-use policies to guide future development in transportation and infrastructure. 

“There’s two components of Climate 2050. One is emissions reduction and looking at low-carbon options. The other is climate adaptation to make sure our region is resilient to the impacts of climate change going forward,” says Dana Zheng, a program manager with Metro Vancouver Liquid Waste Services. Zheng worked on the development of the infrastructure plans made to support the region’s climate strategy.

“There’s a lot for us to understand and gather information on before developing these options. It’s, unfortunately, a lengthy process, but in my opinion necessary to know that we’re doing the right thing,” says Zheng. 

Metro Vancouver is also participating with the Fraser Basin Council in collaboration between all levels of government to develop regional flood risk assessments as part of the Lower Mainland flood management strategy.

“The objective of this strategy is to develop a unified approach to reducing flood risk and improving the resilience of our communities,” she says. 

“Part of this initiative is agreeing on a set of flood mapping and identification of flood mapping within the region, so that we’re all using the same resources and updating these resources as information becomes available.” 

This information could be used to inform developments in the region to prevent damage to at-risk areas in cities like Delta, which is currently in the process of increasing the height of dikes that protect areas at risk of flooding.

“There’s ongoing work to reinforce the Boundary Bay Dike. That’s been a multiphase project that we’ve been successful to get federal funding for,” says Mike Brotherston, manager of climate action and environment with the City of Delta. 

Delta applied for a federal disaster mitigation and adaptation fund for Ladner Village to increase the height of the Chisholm St. road that goes along the water and dike, and to improve the pump station in that area. Brotherston says the whole project is estimated to cost $19 million, and the federal funding would cover 40 per cent of the cost. 

Delta’s engineering team is looking into what can be done along the River Road route, doing consultation with residents and seeing how the dike’s height could be increased and improve cycling infrastructure. 

Surrey received some federal money from the disaster mitigation and adaptation fund for multiple projects, including one in Mud Bay, which is south of the Boundary Bay Airport and west of Crescent Beach, that involves building up the foreshore and the dike within the intertidal area. 

By increasing offshore height and following the living dike concept, which incorporates the surrounding environment and natural species to minimize loss of coastal ecosystems, the idea is that it will break the waves on their way in, Brotherston says. If successful, the design could be used elsewhere in the world to reduce the overall height of waves as sea levels rise.

“But if we combine it with a living dike, it might not need to be as high,” Brotherston says.

There’s a solid economic and business case to invest in dikes, Brotherston says, with billions of dollars worth of infrastructure, industrial, and residential areas within the lowland of Delta.

“It’s quite important to make those investments, and they can certainly pay off when you compare it to the impacts that a flood can have,” he says. 


Acting now to protect the future

Governments have been doing risk assessments and risk mapping projects, so they have a sense of where communities are at the most risk of flooding and sea-level rise, Clark says. 

“More information is needed, but generally, governments know enough to begin acting today.”

Some parts of Richmond and Surrey are at or below sea level and are protected by systems of dikes, but there are homes and buildings built in those areas. Flood risk is important for real estate, and in Canada real estate revenue represents a huge part of the economy. 

“With the cost of real estate here that makes the economic loss far higher too,” says Clark, who feels that there needs to be more conversation around the disparities between those who will be impacted and potentially displaced long-term by flooding.

“More work needs to be done in conversations about managed retreats, making sure that we start to think about where we’re developing homes and real estates, and neighbourhoods, and pull back from areas that are going to flood frequently.”  

The Under Water report also emphasizes the importance of transparency to ensure investors and institutions understand what the risks are in flood-risk areas. The report found that “the amount of climate risk threatening the value of a home or building is equally unknown to the owner, mortgage lender, and mortgage-backed security holder” because the risks are not being widely assessed or disclosed. 

“It’s a real big barrier here. If you’re an individual it’s quite tricky if not impossible to find out what the flood or wildfire risk is for a property that you’re wanting to put your life savings into. That’s an issue.”

The report estimates that at least a half million buildings at risk of flooding in Canada are not identified by government-produced flood maps, and for the flood maps available they are on average 20 years out of date and don’t examine future flood risks due to climate change. 

“Governments and other major infrastructure owners continue to design and build for yesterday’s environment without factoring in climate change risk,” reads the executive summary of the Under Water report. 

“If we want to protect lives and the economy, there’s not an option of just picking one thing,” Clark says. 

“We cannot afford not to act. These costs are coming, and preparing today is the most fiscally prudent approach.”