New construction flood level may be needed all around Okanagan lake

July 11, 2018 July 11, 2018

Anna Warwick Sears doesn’t like the term “new normal” at least as it’s been applied to climate change and the last two years of flooding in the Okanagan Valley.

“New normal implies a static condition but the problem here is there’s a high level of unpredictability with the weather,” the executive director of the Okanagan Basin Water Board says.

Even though outwardly similar — localized flooding followed by a sharp rise in Okanagan Lake — Warwick Sears points out they were both completely different events, despite similar outcomes: high water and damaging floods.

“Last year it was mostly rain driven whereas this year is was mostly snow-driven with a record snow pack,” she says. “Things are not becoming obvious, things are not that easy to predict.”

Both years fit the general model of climate change for the Okanagan with an increase in annual precipitation but a decrease in rainfall over the summer, leading to wilder swings in the weather and more damaging weather events.

As a scientist, Warwick Sears would never count one flood as demonstrative of climate change but one thing that has become clear is the continued viability of the “flood construction level”, the point above sea level where lakeshore construction is supposed to be safe.

“343.66 metres is supposed to be safe but last year the level was 343.25 and that doesn’t include the minimum freeboard allowance to account for wave action,” she points out.

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