After seeing a precipitation deficit through November, the West Coast's wettest month, a ‘potent and impactful’ atmospheric river brings heavy rainfall to western Vancouver Island.
According to Environment Canada, up to 150 millimetres of rain is expected in some areas, with the storm expected to calm in the early hours of Tuesday, Dec. 5.
The River Forecast Centre issued a high streamflow advisory for the west coast of Vancouver Island.
“Heavy downpours can cause flash floods and water pooling on roads,” reads the Environment Canada alert for the west coast of Vancouver Island. “Localized flooding in low-lying areas is possible.”
“It's a pretty broad and wide atmospheric river that's coming in and especially along the west side of the Island,” said Jonathan Boyd, a hydrologist with B.C.’s River Forecast Centre.
He added that freezing elevations are relatively high at 2,500 to 3,000 metres, “which means that if there is snow [on] some of the western Vancouver Island mountain tops, that snow could melt and just add to the water in the systems.”
This atmospheric river may be a positive for the drought conditions, Boyd said, since last week things were reported at level one, jumping back up from zero.
“In the sense that the ground is a little bit drier, and vegetation is kind of ready to soak up some extra moisture,” he added.
“From a drought perspective, the storm actually is, I think, fantastic, aside from of course the localized challenges that may present itself from flooding,” said Boyd. “We do need these atmospheric rivers to replenish the water supply, the reservoirs, the groundwater, and just saturate the soil.”
Though November was in a precipitation deficit, for the Ditidaht First Nation, the main road into their community at Nitinaht Lake has already seen multiple floods, shared Chief Councillor Judi Thomas.
“Ditidaht is impacted in a big way with large rainfalls and storms that happen every year,” said Thomas. “Every year the…Campus Creek floods, blocking the main road access in and out of the village, obviously stopping ambulances, transporting people and groceries in and out of the community.”
“It disrupts transportation and even puts human lives at risk,” she added.
According to James Fothergill, Ditidaht Emergency Services manager, the main road sees roughly 12 floods per year.
But the community now has a 2.8-kilometre bypass road.
Thomas noted that this bypass was put in by logging road builders.
“It does not work well for cars; the grades are too steep. It puts more of our people at risk from a safety point of view,” she said, noting that erosion is a concern. “It's a safety hazard even though it's meant to be a mitigation to the flooding.”
Thomas shared that in November when the main road flooded, trees had fallen across the bypass.
“It raises concerns for access,” she said.
“In November, I met with Minister Fleming to advocate for the overall road improvements for the local community,” said Thomas, adding that she would like to see provincial standard improvements to the road. “We need signage, we need safety measures in place, and this mostly results from the closure at Highway 4, Cameron Lake bluffs, where hundreds of thousands of people were rerouted through Ditidaht traditional territory.”
After a June wildfire shut down Highway 4 at Cameron Lake for much of the summer, Boyd noted potential of debris or a landslide cutting off access again during heavy rain.
“And then thinking of those alternative routes that were being used to get people to Port Alberni and when you get into the logging roads, along with heavy rainfall and heavy use, that's when they become quite dangerous,” he said.
“The remote communities are at greatest risk,” said Boyd, adding in concern for residents and communities living along river systems.
“We already have a feasibility study completed that lifts the road and widens it to provincial standards so that it’s flood proof,” said Thomas, with estimates of the project costing roughly $30 million. “We want to promote safe and efficient movement of people through our territory.”