With words such as ‘bathymetric’ and ‘LiDAR,’ the process of flood mapping the Burnt and Gull River watersheds may sound complicated to residents, but the end goal is simple, County director of planning Steve Stone says.
He told council Feb. 22 the main purpose of the project “is to prevent loss of lives, property and land caused by flooding.”
Following 2013, 2015, 2017 and 2019 floods, the County has partnered with the Ganaraska and Kawartha Region conservation authorities on the work that began in 2017 and is poised to be completed in 2024. The Ganaraska Conservation.
Authority’s Cory Harris and Ian Jeffrey updated council on the project last week.
It started with phase one when they got money under the National Disaster Mitigation Program (NDMP) for LiDAR, an acronym for light detection and ranging, which is laser imaging used to get elevation data. It was done in 2018-19, with data delivered in 2020.
It was also in 2020 that the province launched its flooding strategy in Minden. It called for understanding flood risks, strengthening governance of flood risks, enhancing flood preparedness, response and recovery, and investing in flood risk reduction.
Flooding most significant natural hazard in Ontario
Phase two of the local project involved bathymetric data, which the partners also got NDMP money for. It’s the measurement of the depth of water in rivers or lakes. Bathymetric maps look like topographic maps, with lines to show the shape and elevation of land features.
Work on that was done in 2021-2022.
Phases three and four involve technical work, developing hydrologic and hydraulic models, and the flood mapping itself.
The study area is huge, with more than 2,800-square-kilometres of drainage; 400- plus kilometres of channels; 23 lakes, 42 dams and key areas within the Parks CanadaTSW system.
It’s expected the County will be ready for public consultation in late 2023 and early 2024, when the results of the work can be unveiled.
Stone noted in the province’s flooding strategy, flooding is the most significant natural hazard in Ontario in terms of death, damage and civil disruption and the costliest natural disaster in Canada in terms of property damage.
He said this project will address the number one priority of understanding flood risks and how they can be mitigated and risk-managed.
“The deliverables of this project will include updated, and where applicable, the creation of new flood plain mapping for the reservoir lakes and the connecting rivers that are frequently impacted by flooding,” he said.
“Updated floodplain mapping will be used to reduce the impact of flooding by directing new development to safer locations and regulating legacy development within the floodplain and flood fringe areas.
Enhanced knowledge of the location of the flood susceptible areas will allow the County and local municipalities to plan the most efficient emergency response efforts, reducing the impact of flooding on the population and make our communities more resilient”.