Lost Rivers and Urban Flooding - Review of Flood Risk Factors in Toronto Wards 13 / 14 - Decreasing Extreme Rainfall Trends, Increasing Urbanization and Intensification. Financially unsustainable green infrastructure.

Toronto Wards 13 / 14 Lost Rivers Overland Flow Paths
(image can be downloaded using link at bottom of post)

The following presentation to Toronto's Green 13 group explored the role of 'lost rivers' like Ward 13/14 Wendigo Creek and Spring Creek, in driving urban flood risk. Urbanization and intensification are revealed as key factors affecting runoff rates and flood risk. Extreme rainfall trends are shown to be decreasing in Toronto and other long term Ontario climate stations, indicating no impacts due to climate change. Variations in runoff rates are shown to be explained by changes in urbanization that increase runoff coefficients in the Don River since the mid sixties, as urbanization and intensification have increased. Insurance industry claims of more frequent severe weather are shown to be disproved by Environment and Climate Change Canada's Engineering Climate Datasets.

Lost Rivers & Urban Flooding, Media, Myths & Smart Mitigation - Toronto Wards 13 / 14 - Presentation to Green 13 from Robert Muir

Toronto lost rivers (aka overland flow paths) can be explored on the following interactive map - map is (c) CityFloodMap.Com. Note, approximate TRCA regulation boundaries were estimated from camaps.ca georeferenced image features, and TRCA shoreline/slope regulation areas and some natural heritage regulation areas have been excluded to focus more on where river flood risks exist:

View larger map

The Green 13 meeting handout illustrating Toronto Ward 13 / 14 lost rivers and overland flow paths is available at the following link:  handout file