With Eastern Canada under water, is BC due for more flooding?

Laurie Tritschler, with files from Mohak Sood / April 29, 2019

Canadian Red Cross volunteers are helping flood victims across Ontario, Quebec, and New Brunswick.
(Twitter / @redcrosscanada)

British Columbians will remember the catastrophic flooding that inundated the interior city of Grand Forks last May. Should the province expect a repeat in 2019?

No, says the BC River Forecast Centre’s David Campbell.

Campbell oversees the weather modelling the Centre users to predict annual flood conditions. He attributes last year’s flooding in Grand Forks to a high snowpack, unseasonably warm weather, and heavy rain which unleashed a deluge along the city’s Kettle River. While Campbell says Spring rain storms are “always a wild card,” he reports this year’s snow pack was at 79% of last year’s levels at the start of April. Meanwhile, prevailing weather patterns aren’t likely to trigger a massive run-off of snowmelt.

Campbell adds the increasing incidence of major flooding in BC is likely due to the effects of climate change.

While the province’s interior can expect more flooding in years to come, declining snowpacks on the Coast Mountains are expected to produce more droughts in the lower mainland.

Droughts are “more of a slow-moving hazard,” says Campbell, but water-shortages require more long-term conservation measures and can pose serious risks to fish and wildlife species—and certainly human populations—when conditions get extreme.

It’s a mild spring ahead for British Columbia—not so for much of the rest of Canada. Severe flooding has forced thousands from their homes and businesses across Ontario, Québec, and New Brunswick.

Southern Ontario braces for more flooding

The Ottawa River is threatening the nation’s capital, where Mayor Jim Watson declared a state of emergency last Thursday. Hundreds of Canadian Armed Forces’ troops were deployed at the city’s request, with troops arriving Friday.

The Rideau Valley Conservation authority, which monitors the area’s watershed, reports incessant rain is significantly adding to this spring’s snowmelt, swelling the Lower Ottawa River and most of its tributaries. Up to 40 millimeters is expected to fall over the region between now and Thursday, with up to 20 millimeters expected for Friday alone, according to the RVCA website.

With levels peaking tomorrow or Wednesday, the flooding is expected to be worse than in May 2017, when the Ottawa River Regulation Planning Board reports having seen the highest water levels in many areas since recording began in 1950.

Québec’s Laurentian Valley under threat

In Québec, flooding along the Saint Lawrence River has inundated much of the region surrounding the city of Gatineau.

Meanwhile, Montréal Mayor Valérie Plante declared a state of emergency last Friday afternoon.

Conditions worsened Saturday night, when the nearby Lake of Two Mountains breached a natural dike protecting the suburb of Sainte-Marthe-sur-le-Lac. An estimated 5,000 residents fled the area without warning, with Québec Premier François Legault saying it was “almost a miracle” no one was hurt.

Over 5,500 homes have been flooded province-wide as of this afternoon.

Floodwaters in New Brunswick to recede

Flooding has stabilized in much of the province, though heavy swelled the Saint John River near Fredericton on Saturday night. Recent forecasts predict water levels will slowly recede throughout the week, but the Emergency Measures Organization warns communities are still flooded between the capital and the city of Saint John.

Spring floods are not unprecedented in Canadian history, but EMO Director Doug MacCallum has also speculated this year’s extreme flooding indicates a worrying “new normal” brought by climate change. The story map below illustrates the gathering trend.