No link found on climate change, Bow River floods

Flooding is a natural phenomenon needed to replenish ecosystems and ground water.

Yet it can cause catastrophic damage because recent housing and other urban developments have been built on floodplains.

“There are ecosystems that actually depend on these high flows,” John Pomeroy of the University of Sask-atchewan told the Canadian Water Resources Association annual meeting held in Calgary March 24-25.

Eighty percent of Alberta’s water supply is derived from snow melt. Floods in the Bow River watershed are caused by snow melt, rainfall and ice jams.

Jennifer He of the University of Calgary’s engineering school, is investigating whether recent floods can be attributed to climate change and whether extreme weather events are becoming more intense and frequent.

Her preliminary research has not found a significant connection to warming trends or snowfall amounts.

She did find that the December-March period is growing warmer, but more analysis is needed to determine if climate change has had a meaningful affect in the Bow River watershed.

The history of the Bow River basin and the Red Deer River watershed shows that floods are common.

However, graduate students from the University of Lethbridge have found historical gaps, so it is hard to determine the intensity of past events.

High River, which has been deluged many times, is located on a broad open flood plain with no valley, which makes it prone to flooding.

Stephen Foster, a graduate student studying environmental science, had first-hand experience with last year’s flood when his family’s home on the east side of the town was flooded.

“Will we see it again? Most likely. These floods seem to be predictably big,” Foster said. “Large floods are predictably frequent for this area.”

The Little Bow River originates in the middle of the town and flows into the Oldman River. His research found major floods in 1923, 1929, 1932, 1942 and 2005.

However, information on how much water was discharged during these events is lacking, which makes it hard to calculate what needs to be done to protect against future events.

The Little Bow channel was widened after last year’s flood and is not well defined.

New structures are needed in the region to handle higher stream flows, and the community is developing protective berms and spillways.

The Red Deer River did not flood, partly because it did not receive as much precipitation, said student Laurens Philipsen.

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