Agricultural drainage | Farmers who hold water on their land are providing a service
Water expert John Pomeroy says paying farmers to store water might curb unauthorized drainage and alleviate some of the problems that go along with it.
The Canada research chair in water resources and climate change, based at the University of Saskatchewan, said he understands why farmers want to get rid of the water.
But widespread drainage isn’t doing much to help anyone downstream. Agricultural drainage has been singled out as a contributor to the recent flooding in Saskatchewan and Manitoba.
Manitobans have blamed Sask-atchewanians for dumping water on them, particularly through the Assiniboine River system. And even Saskatchewan premier Brad Wall said last week that drainage exacerbates the problem.
The province is working on new drainage regulations but they aren’t expected until 2015.
“We have to strike a balance because this is private property,” Wall told reporters in Regina. “However, we also need to be concerned about public safety.”
Pomeroy doesn’t completely blame farmers for the prairie floods that have ravaged parts of all three provinces the last few years.
“I’m not trying to paint them as the enemy at all in this,” he said in an interview last week.
“They’re stuck in a very difficult situation. My feeling is that they should be compensated for (holding back water).”
He said farmers who hold water on their land are providing a service.
However, the economic incentive is to grow crops, not keep water.
Pomeroy spoke to the Saskatchewan government a couple of days before the most recent rain and flood to discuss the results of a study on Smith Creek in east-central Saskatchewan, which drains into the Assiniboine River.
The area southeast of Yorkton has been extensively drained and there was a perception that the hydrology had changed. Both the Saskatchewan and Manitoba governments helped pay for the study in a bid to better understand what is happening.
The study, which used LIDAR, an airborne laser measuring technology, actual stream flow measurements and hydrological models to run scenarios, found that both the changing climate and drainage have affected the Smith Creek basin.
Pomeroy said hydrology and climate data from the 1940s to the present show the snow melt occurs three weeks earlier now, the winter temperature is up four or five degrees, and there is a shift from snowfall to rainfall in March.
Summer rainfall has shifted significantly. Single thunderstorms, often damaging but not flood-causing, have been replaced by multiple-day rainfalls that cover a large area and do lead to widespread flood.
“This storm is an example of one,” he said of the late June event. “In the Yorkton area they’ve increased in frequency by 50 percent since the 1940s. That’s a big change.”
He also noted the overall amount of precipitation has not changed over time.
“It’s the way it’s coming down that’s changing. That’s the primary driver of the flooding.”
But, when that occurs in conjunction with wetland drainage, the situation becomes worse.
“If (drainage) wasn’t occurring then the modest flows in a creek like Smith Creek would be a little bit higher and it probably wouldn’t be an issue at all,” he said.
In 1958, wetlands covered about 24 percent of the Smith Creek basin. Now they cover only 11 percent.
“Drainage of existing Smith Creek wetlands increases the 2011 peak flow by 78 percent and the 2011 flow volume by 32 percent,” Pomeroy said, referring to the flood of record.
“It’s kind of scary,” he said.
The report says restoring wetlands to 1958 levels would decrease the yearly stream flow volume by 29 percent and the peak flow by 32 percent.
“Overall, Smith Creek total flow volumes over six years increase 55 percent due to drainage of wetlands from the current (2008) state, and decrease 26 percent with restoration to the 1958 state,” said the report.
It also notes that wetland drainage has “an exceptionally strong impact” on stream flow in normal to dry years.
Pomeroy said restoring wetlands could help the situation.
Work he’s done in the Vermilion River basin in Alberta showed that focusing on the lower part of watersheds where the biggest sloughs are would likely be most effective.
“The farmers there are the ones driving it,” he said of restoration projects in that basin. “They wanted to see the watershed functioning as close to its natural state as possible.
“It’s very different from the conflict we get in eastern Saskatchewan sometimes.”