Last week’s torrential downpour dropped at least four inches of rain in communities across Southeastern Manitoba — including Steinbach, La Broquerie, and Mitchell. Some residents reported even more.
Manager at the Seine Rat Roseau Watershed District (SRRWD), Joey Penkiw, says this isn't the first time that we've seen a rainfall event like last week's storm in the last few years, which is concerning because it likely qualifies as a “one-in-100-year” event according to their models.
"I think since I have been at the district since 2019, that is about the third event of that level of rain in September that I have seen. So, we say 1 in 100 years, but these kinds of events are happening more and more often."
District duties
The SRRWD is responsible for land and water management across three watersheds, the Seine River, the Rat River, and the Roseau River.
Many of their projects focus on agriculture and working with producers to improve water quality and management.
These efforts aim to balance human activity with the natural flow of water to prevent flooding and protect the land.
Modeling water flow
A key tool in the district's toolkit is LiDAR (light detection and ranging), a remote sensing technology that showcases information about elevation throughout the region.
“We can pretty much take a rainfall event and put it on the ground through the computer, and we’ll get a model back explaining where water is most likely to pool,” he explains.
He notes this technology helps SRRWD identify where water problems occur and how they can be mitigated in the future.
“We try to do a one-in-10-year event, one-in-25-year, one-in-100-year, so we have that kind of capacity within the district to know where we have flooding problems. Then we can see the impact that a dry dam might have if we put it in,” Penkiw explains.
Dry dams
A dry dam is a structure that the SRRWD uses for the purpose of flood control.
“A dry dam usually has a controlled culvert."
This allows less water to flow through the culvert during normal rainfalls. During periods of intense rain, the dams hold back excess water, releasing it later at a controlled rate.
“These dams also have a spillway. So, if we get an event like we did last week, that water can rise and then it has an emergency spillway to exit through,” he notes.
Penkiw says these dams are to store the water for a few additional days.
“We’re trying to take the peak flows off the local drainage systems and allow them to have a chance to empty out before we send that (excess) water downstream.”
Land over time
“In the three watersheds, we’re seeing dramatic land use changes,” says Penkiw.
“In the past, these areas would have been covered with forests, lots of little wetlands. And what we’re seeing over the past few years is a lot of deforestation, changing agriculture from grazing to crop farming. These areas used to have that built-in sponge that absorbed water.”
He notes many drainage systems in this area were designed many decades ago and weren’t meant to handle all the water it’s taking now.
“There’s literally no way — without spending millions and millions of dollars — to update these drainage systems. It would be financially impossible to improve them enough to make the dramatic increases we need to see,” he explains.
“We have to look at different ways.”
Working together
Local RMs like La Broquerie, Hanover and Mitchell all partner with the SRRWD to streamline communication and problem-solving.
“I think we need more cooperation like that. I think we need more conversations together with all our partners to make some better impacts in the community,” Penkiw says.
While no system can perfectly handle extreme rainfall like last week’s storm, he notes there are steps that can lessen the damage.
Penkiw says the work of the SRRWD signifies the importance of planning, community, and rethinking how we interact with the natural systems around us.
Written with files from Kenton Dyck
Check out this interactive map which includes recent SteinbachOnline articles and photos from the rain and flood event.