Climate data suggests weather patterns are changing and flooding on the Assiniboine River may become more frequent, says John Pomeroy, director of the University of Saskatchewan’s Centre for Hydrology.
It’s not just the three consecutive years of heavy spring rains that concern the professor, who is also a Canada research chair in water resources and climate change.
A recent study of 100 years of rain and snowfall data on the Prairies shows smaller, one-day rainstorms are giving way to multiple-day intense events covering a vast area.
“Those larger storms are the ones that cause the flooding like we have seen on the Assiniboine this spring,” said Pomeroy.
“The change has been occurring over a long period of time, but it appears to be accelerating over the last little bit since 2004.”
The range of recent events, he added, has been “completely off the scale” of historical norms based on measurements that began in the 1890s.
Recent papers by atmospheric scientists have shown a northward movement in the jet stream in the summer, and greater penetration of moist air from the Gulf of Mexico into the eastern Prairies. That is causing large, more intense storm fronts.
“We didn’t have that occurring as much a few decades ago. So eventually we are going to have to adapt how we manage our water to that,” he said.
A government official says the province is aware of the data and an analysis of April to June rainfall data going back to 1970 found this year was the wettest in modern times.
“Shellmouth Dam has never experienced such wet conditions in these three months since it started operating in 1970,” said a spokesperson for Manitoba Water Stewardship.