Blog dedicated primarily to randomly selected news items; comments reflecting personal perceptions

Tuesday, July 08, 2014

Calamitous Climate

"It's utterly unprecedented."
"And this one is blowing all the others out of the ballpark."
"Everything we know about hydrology on the prairie appears to be different. We never have saturated spongy soils with flow running off farmers' fields in the midsummer. Never."
John Pomeroy, director, centre for hydrology, University of Saskatchewan
Recovery help on the phones

Floodwaters surround cottages and homes on Crooked Lake during Saskatchewan Premier Brad Wall's aerial tour of flood-ravaged southeast Saskatchewan last Wednesday, July 2. Nearly 90 communities in Saskatchewan and Manitoba have declared emergencies because of flooding and more than 500 people have been forced to leave their homes. Photograph by: Don Healy,  The Leader-Post

Dr. Pomeroy holds a Canada research chair in water resources and climate change. His professional assessment is that three floods -- one currently unfolding in Saskatchewan and Manitoba and an earlier one in southern Alberta taking place a year after high flood waters ripped through Calgary, causing Canada's costliest natural disaster up to then with over $6-billion in damage -- have been caused by storm fronts laden with moisture that moved up from the United States, then "stalled".

That stall was a disaster for the landscape under the stalled storm fronts. Torrential rain came down over large areas for days, seemingly never to end, and in the process saturating soil, funnelling the runoff into streams and rivers, which overflowed inundating fields. In the process washing away roads and flooding entire communities.

The natural ecology of the landscape had been altered over generations of farming by land owners draining natural slews and wetlands. The result was instead of retaining excess moisture falling out of overloaded skies, water ran off fields more quickly than they might otherwise have done. But who might have predicted the extreme weather events that appear over the past decade to surprise everyone whose geography has been impacted?

That increase in stalled summer storms "that just sit there" appears, from what Dr. Pomeroy is able to discern, to be linked to a shift in the jet stream and atmospheric flows. This is a phenomenon that may well be responsible for much of the extreme weather that has been ricocheting around the Globe; the prolonged deep freeze last winter in central North America, Australia's heat waves and the monsoon-like rains that inundated Britain earlier in the year.

This "regime shift" has impacted the Prairies which are far more accustomed to short sporadic summer thunderstorms; generally over from start to finish in a matter of minutes, not incessant rains lasting or days. Historically it has been spring snowmelt, not summer rain that has caused Prairie floods. The past decade has seen a shift to "rain-derived floods."

He and his research team have documented the change through a research program in the Smith Creek Basin in southeast Saskatchewan flowing into the Assiniboine River, which is now causing untold misery with countless homes and farms in Saskatchewan and Manitoba now labouring through a state of emergency with the province calling in the military to aid the province in dealing with the overwhelming flood conditions.

Normally, streams and creeks in east Saskatchewan begin their flow in March, then peak in April and dry up by early May once the snowmelt is completed and that is reflected in records that date back to the 1950s. While Smith Creek is generally "bone dry" by July, last week it hit a never-before-seen high of 24.5 cubic metres of water a second roaring downstream.

Floodwaters invade a farmstead near Gainsborough,SK during Saskatchewan Premier Brad Wall’s aerial tour of flood-ravaged southeast Saskatchewan on July 02, 2014. Nearly 90 communities in Saskatchewan and Manitoba have declared emergencies because of flooding and more than 500 people have been forced to leave their homes
Don Healy/Postmedia News -- Gainsborough, Saskatchewan

Heavy winter snow -- heavier than most winters last year -- had saturated the soil, and then came a heavier-than-usual spring rain season. When the frontal system looming up from the U.S. stalled over southeast Saskatchewan in late June it "pushed it over the top". More than 150 millimetres of rainfall in a few days; that much rain normally falls in dry southeast Saskatchewan in the space of a year.

Dr. Pomeroy speaks unkindly of the stark lack of a national Canadian strategy and program for improved flood prediction and water management. He cites recent cutbacks by the federal government, and the "gutting" of federal hydrology climate and flood management programs leaving the country ill-prepared to predict and cope with the fallout of changing weather patterns.

"Every province is left on its own, with some doing better than others."

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