Flood Risk Management

By Tamsin Lyle and Deborah Harford

Originally published in Construction Business: BC and Alberta’s Construction Magazine, March/April 2015 Vol 12. No. 3

Overland flooding is consistently Canada’s most costly and frequent natural hazard, posing catastrophic risks to Canada’s economy, infrastructure, environment, and citizens. This will only worsen due to the changing climate. Recent loss estimates from the insurance industry for a catastrophic flood in BC range from $7bn-$10bn.  In Alberta, the 2013 floods in the southern part of the province cost in the order of $5bn.  Unfortunately, lack of dynamic action on flood planning by senior governments is exacerbating the risks posed by such events for millions of Canadians.

Water on a floodplain itself is not a problem. Damages occur when water negatively interacts with natural and human environments, impacting buildings, agriculture, critical infrastructure, business activity, transportation networks, and occasionally even human life.

It is well documented that preparation and planning ahead of a disaster will greatly reduce cost and suffering during and after a flood.  However, without knowledge of where, and what, the risks are, such actions are hard to implement. The estimation of flood risk is complex and often poorly understood.  It is a function of both the likelihood of an event occurring and the consequences of that event occurring, where consequence is defined as a function of flood hazard (where will the water go?) and vulnerability (what’s in the way?).    Flood risk assessment, although complex and resource-intensive, is widely considered to be the best tool with which to make decisions that can reduce impacts.

A true flood risk assessment is invaluable for decision-makers, as it considers consequences for a range of potential events and time-scales; particularly useful information when considering long-term investments in infrastructure. Unfortunately, it is not widely practiced in Canada, partly due to a lack of established standards and senior level government oversight, partly because the professional community is entrenched in the use of older methodologies, but the biggest obstacle of all is the fact that there are not enough dollars available to carry out adequate analysis.  Despite the fact that spending the dollars now will save billions down the road.

What can we do to reduce the risk?

Water will occasionally escape the confines of rivers and creeks and flow overland; there are no effective means to stop water from flowing downhill, although engineered structures like dams and dikes can slow and direct the flow. Given that there are limited opportunities to change the hazard, there is a need to focus on reducing the vulnerability of assets and people on the floodplain.

In the wake of large flood events around the world in the last few years, there has been a significant move towards the discussion of resilience in the face of disaster, as opposed to risk mitigation.  In short, policy-makers are acknowledging that they cannot control the hazard, and that because of historic developments they cannot sterilize floodplains.  Instead, they are looking at the best means of minimizing damage and of recovering faster after an event.  There are many dimensions to resilience, including social planning; for example, investing in social networks so that neighbours can help neighbours. Physical responses are also being promoted, for instance Property-Level-Protection, where individuals are provided resources to improve the resilience of their homes through smart building design.

Why is Flood Risk Increasing?

Unfortunately, the risk of flooding in Canada is on the rise.  This is partly because the hazard is changing with climate, and partly because the vulnerability is changing as floodplains are built out. A highly under-resourced flood management system across the provinces and country is also a contributing factor.

Lack of Information

It may seem surprising, but most of Canada lacks information about where floods are likely to occur. In response to concern from insurance agencies following severe floods in Calgary and Toronto in 2013, the federal government has begun to examine national flood map capacity. In BC it was reported that only 50% of required mapping has been completed. Furthermore, the mapping that does exist is out of date as it does not include climate change projections, nor any other physical changes to the rivers and floodplains. The U.S. Federal Emergency Management Agency’s Risk Map project advises that maps should be reviewed every five years at minimum; in BC, the median age of provincially-designated maps in 26.

Reactive versus Proactive Initiatives

There is great urgency for senior level governments to help communities and industry better manage flood risk, especially in a changing climate. To date, however, uncertainty as to when and where floods will occur has resulted in limited political will to act, as pro-active responses may not bear fruit for decades. And, therefore the status-quo is to sideline planning initiatives, and instead bail out affected individuals, businesses and local governments when floods occur – at the cost of many billions of dollars a year that are ultimately paid by all Canadian taxpayers. Given the storms projected in a changing climate, a growing population, and the resultant increasing flood risk, this will become an increasingly expensive burden for Canadians to bear.

Conclusion

The complexity of the problem and our current state of affairs shouldn’t be seen as an insurmountable barrier; it can be overcome with judicious use of resources ahead of a disaster.  Climate change may be the catalyst needed to drive acknowledgment of flood risk in design and planning, which, if paired with best practices in engineering design and construction, will contribute enormous value to other important aspects of community liveability and resiliency.

Given the increasing obviousness of the benefits of adaptive planning, and the crippling costs of the existing reactive response to flooding, flood risk in Canada will have to be reduced in the next few years.  This can be achieved through continued pressure on senior governments to engage in the issue, and through the enormous capacity of engineers, planners and architects to innovate in the face of adversity.

Bios

Tamsin Lyle is principal engineer and flood specialist at Ebbwater Consulting in Vancouver.  She has worked on flood management throughout her academic and professional careers.  She can be contacted at tamsin@ebbwater.ca

Deborah Harford is executive director of ACT (the Adaptation to Climate Change Team) in the School of Public Policy at Simon Fraser University. Deborah’s work with ACT has gained her national recognition as a resource for those seeking information on climate change adaptation and practical coping strategies. She can be contacted at adapt@sfu.ca