Government researchers nearly finished regional flood mapping

With most of the groundwork now complete on the two-year Medicine Hat River Hazard Study, government researchers turn their attention to the actual flood map generation, scheduled for completion in the spring of 2019.

“The goal of the program is to enhance public safety and reduce flooding through the identification of river and flood hazards,” says Alberta government flood hazard specialist Peter Onyshko. “The province of Alberta has been making flood maps since the late 1970s.

“We’re working on 11 studies across the province, and we started doing studies of this type after the 2013 floods. So Medicine Hat was one of the candidate communities, and it was just kind of time for Medicine Hat and the South Saskatchewan River to get some new and expanded mapping.”

Last fall, two boat crews and a ground crew supported by aerial LiDar (laser mapping) surveyed 40 km of the South Saskatchewan River, 24 km of the Ross Creek, 23 km of the Seven Persons Creek and 10 km of the Bullshead Creek in and around Medicine Hat to build up a complex picture of local river systems and flood planes.

“We surveyed cross-sections on the river,” explains the Hazard Study’s project manager Jim Choles. “We also collected LiDar data which shows us elevation, and we create mapping from that.

“Then we create a hydraulic model we can use to predict water levels, and then we do a hydrology assessment to assess the river flows from the one in two-year flood all the way up to the one in a thousand-year flood.”

When completed the project, co-funded by the federal government’s National Disaster Mitigation Fund and Alberta’s Provincial Flood Hazard Identification Program, will give local municipalities access to better information than ever available before on potential flood conditions at various cycles of southeastern Alberta river systems.

“We are quite certain these maps will be useful to all local municipalities,” Onyshko says. “Alberta has been providing flood maps to communities for the past 30 years, and our experience is the flood maps we have been able to provide are always useful.

“The new studies we are doing now really expand the number of different types of flood maps we are providing, and the different flood scenarios. We will have 13 different flood flows covered by this hydrology model, and corresponding maps showing what would be flooded for a wide range of different flows.”

For more information on the Medicine Hat River Hazard Study visit floodhazard.alberta.ca.