Wet today, wet tomorrow — and spring flooding again a threat

Flooding near Oliver in 2017. (Susan Pement photo)

After enduring a spring and summer of flood and fire last year, you’d think the Okanagan would deserve a break this year.

Apparently, that may not happen.

The provincial River Forecast Centre says there is “an increased risk of flooding” this spring as over-burdened snowpacks in the Okanagan and Similkameen begin to melt and weather is expected to remain warm and wet.

The early warning signs have Emergency Management BC issuing an early caution for BC residents in areas prone to flood risk.

“Nearly 80% of the annual BC snow pack typically accumulates by early March,” the centre reports in its March 1 forecast. “Very high snow packs (>135%) in the South Interior (including the Skagit, Similkameen, Okanagan, Boundary and Upper Fraser West), and high snow packs (>120%) in the Kootenay indicate an increased seasonal risk of flooding.

“Given this year’s La Niña conditions, it is unlikely that the risk will ease much prior to the melt season.”

The snow pack is reported at 144 percent in the Similkameen and 141 percent in the Okanagan.

Seasonal volume runoff forecasts are expected to be well above-normal for the Okanagan, Similkameen and Nicola.

“Changing temperatures, melting snow and higher-than-normal precipitation all contribute to the threat of landslides and flooding, especially when high temperatures converge with significant rainfall and rapid snowmelt,” said Jennifer Rice, the Parliamentary Secretary for Emergency Preparedness. “This is a situation that created challenges for much of the Interior last spring.”

 

In 2017, spring flooding forced more than 2,500 BC residents from their homes and threatened thousands more with evacuation alerts.

“By the time the floodwaters receded, Emergency Management BC had dispatched more than 4.4 million sandbags and deployed kilometres of temporary dike structures to the Okanagan region,” said Ms. Rice. “Despite these and other interventions, many communities are still mopping up almost a year after the floods began.”

Although there’s no certainty extreme conditions that caused so much trouble in 2017 will return again in 2018, the province isn’t taking any chances.

“While a high snowpack does not necessarily lead to a particularly active flood year, it’s been a long, cold winter, and the River Forecast Centre is keeping a close watch on snow melt and water levels,” said Ms. Rice.

Elsewhere, the Ministry of Forests, Lands, Natural Resource Operations and Rural Development is reviewing mitigation proposals for construction of protective earthen berms, creek channelization or debris retention basins, and ensuring bridges and culverts are ready.

The province is also reviewing a report on the 2017 flooding — especially in the Okanagan region — to determine if efforts made by provincial staff were sufficient to curb the threat.

The Ministry initiated the independent review by Associated Environmental Consultants Inc. to determine the effectiveness of the ministry’s flood response and to see what could have been done differently to reduce flooding impacts.

Despite the severe weather, the overall findings of the report conclude that the Okanagan Lake Regulation System, Kalamalka Lake and Nicola Lake were managed professionally and appropriately by ministry staff, and that the decisions made by staff were operationally sound.

That report, however, does suggest the BC River Forecast Centre is “under-staffed.”

Locally, it also noted that “due to high Okanagan River inflows and high Similkameen River inflows, Osoyoos lake reached unusually high (but not historic) levels — and suggests flooding in the Okanagan could have been much worse if Mother Nature hadn’t intervened.

“June was much drier than normal and no precipitation was recorded during July and August. If summer conditions had not turned so quickly from wet to dry, flooding in the Okanagan region would likely have been worse,” the report concludes.

 

 

 

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