Drainage contributing to flooding

An expert on hydrology and climate change believes the recent flooding in Saskatchewan and Manitoba has been exacerbated by the widespread drainage of agricultural lands that have increased water volumes that flow downstream into Manitoba.

"The short answer is, yes I do,'' said John Pomeroy, Canada research chair in water resources and climate change and director of the Centre for Hydrology at the University of Saskatchewan.

Pomeroy, who has studied water volumes on the Smith Creek watershed over the last 55 years, says agricultural drainage of sloughs and other wetlands appears to have been one of the factors in the recent flooding. "The volume of streamflow is basically doubled from what it was if the wetlands had stayed intact in 1958,'' Pomeroy said. "It looks like the peak flows have increased about 30 per cent from that.''

Pomeroy said the Churchbridge-Langenburg area has seen it wetlands reduced from 25 per cent in 1958 to 10 per cent in recent years. "There's been a lot of drainage there ... It gives us some idea of the impact of drainage in a lot of the Assiniboine (River system),'' Pomeroy added.

Pomeroy said the floods in 2011 and 2014 have seen the confluence of several factors, including multiple days of persistent rainfall in summer, while previous floods were due to excessive snowmelt in the spring.

"This is what's making it a perfect storm,'' Pomeroy said. "There's been a lot of difficulty in estimating the flood peaks because things like this (agricultural drainage) are making older observations more difficult to interpret. So we're seeing something that is — it's a cliché to call it climate change — but that's exactly what this is."

And he believes the Saskatchewan government should be doing what the Manitoba government has done by bringing in stiff penalties for illegally draining farmland. "Manitoba made it (unauthorized agricultural drainage) against the law on June 10 with really strict regulations and big fines.''

He said farmers should also be given incentives to preserve wetlands. "Public policy should have rewards as well as penalties. Right now, we're not doing that."

Deputy Liberal Leader Ralph Goodale said the federal government also needs to play a role in bringing the provinces together to jointly manage watersheds that cross political boundaries. Goodale said "getting some rational, co-operative control over on-farm drainage will be a key element of any larger vision." Federal agencies, like the Prairie Farm Rehabilitation Administration, would be well-positioned to perform this role, but "thanks to (Prime Minister Stephen) Harper, the PFRA is dead,'' Goodale added,

The Green Party of Saskatchewan is also calling for a southeast drainage study. "A drainage study would produce vital information on needed improvements to bottleneck areas, like around Carnduff,'' the party said in a press release.

Patrick Boyle of the Water Security Agency, said illegal drainage is something that the agency is "looking at in our 25-year plan." But he said "it's too early to tell'' if drainage contributed to this year's flooding.

Source: Leader Post

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Taxonomy

• Environment
• Flood Management
• Hydrogeology