Flood-risk maps need urgent update
Re: “Province: rebuild at own risk; Flooded homeowners warned of ‘consequences’ next time,” the Journal, July 15. “Floods are acts of God: flood losses are the results of acts of humans,” says American flood plain management guru Gilbert White.
His statement is exemplified by photos of downtown Calgary featuring construction cranes surrounded by flood waters. The enormous damage caused by a hydrologically modest flood shows Calgary’s vulnerability to more significant floods in the future. Other Alberta communities share that vulnerability.
So the announcement this week by Municipal Affairs Minister Doug Griffiths that the province will curtail redevelopment in high-hazard flood areas is a welcome step forward. That said, there are two concerns with the minister’s timely announcement.
First, the flood-risk studies for the more than 60 flood-prone communities in Alberta are, in some cases, decades old. These studies need to be revisited.
New technologies, improved computer models, recent floods, and the fact that floods may no longer entirely be considered acts of God are all reasons to examine urban flood risks.
Such a study would show that not only has the risk of floods increased but also the damage arising from them. Thus the urban floodways shown on the Alberta government website are undersized and the elevations for safe building are too low. There’s an urgent need to incorporate findings from the 2013 floods in southern Alberta into the flood-risk maps.
Second, the 2006 Alberta Building Code, like the National Building Code on which it is based, contains no information on requirements for flood-proofing houses. This deficiency is based on the naive expectation that Canadians won’t build houses in flood plains. We all know how well that has worked out.
Some flood-proofing measures, like installing backflow preventers on drains leading from flood plain residences, are almost self-evident now. There are other measures involving materials and practices that require careful consideration and prompt adoption if new houses in flood plains are to meet the test of time.
More attention to building codes could also lead to an all-hazards approach. In parts of Alberta it would make sense to install hail-proof roofs or tornado straps on flood-plain dwellings when they are rebuilt.
The Alberta government has shown a commendable willingness to inform citizens of their vulnerability to natural hazards.
Now Albertans need the tools so they can take responsible actions to reduce that vulnerability.