Toronto Overland Flood Visualization Using ArcScene - Hydrology and Hydraulics in Urban Areas Explain Reported Flood Risk overland flood risk analysis across the City of Toronto has been used in ESRI's ArcScene software to visualize at risk neigbourhoods and vulnerability zones where the correlation of urban overland / pluvial flooding and surcharged sanitary sewers resulting in basement flooding has been established. Flood risks exist beyond large regulated valley systems with a continuum of risk existing from river flood plain to individual building floor drain.

Additional visualization below includes identification of building structures within the estimated overland flood risk zone.

Open During Construction - Podcast on City-Building Brings Engineering and Planning Perspectives to Topics of Today

Happy Birthday to Open During Construction podcast! We are one year old sharing planning and engineering perspectives on city-building. Engineer and moderator Muneef Ahmad, planner Michelle Berquist and yours truly, blogger/engineer Robert Muir, explore topics of the day .. and those who read this blog can listen to my perspectives on those topics from a more personal side.

My Mr Holden's Glen Ames Grade 7 Toothpick Bridge.
Still standing strong! Admire my early truss work in\the deck!
Marvel at the distribution of load in the abutments.
Like? How did this Grade 7 toothpick bridge inspire me to become an engineer (I can trace the success of this bridge project that supported a brick in Mr. Holden's Glen Ames class, to Dr. Prior's Malvern Collegiate Grade 13 physics class 'beam problems' (i.e., engineering statics), to Mark's Experiments in Gothic Structure book review exploring the role of flying buttresses and pinnacles (form follows function!), to enrollment in Civil Engineering at the University of Toronto, to .... OK, so its not as exciting an origin story as Wolverine or something like that but that is why I am here. 

Quick downloads of season 1 episodes are available here:


Power to the Sheeple (we explore ingrained falsehoods in engineering including the insurance industry 'data' on extreme weather that many "sheeple" are following without question)

Like Millenials (we discuss two different types of people who won’t amount to much: People who won’t listen to what they’re told, and; People who don’t do anything but what they’re told - and explore the need to master your craft first (doing what you are told), gaining a strong understanding of assumptions and weaknesses, then committing to making it better (do more than only what you are told))

The Day After Tomorrow (we explore the role of experts like planners and engineers in storytelling, and bringing facts to discussions like the Toronto GO Train flood in 2013 and misreporting of flood frequency in the media) 

Dancing About Infrastructure (is it possible to celebrate infrastructure? how can we help the public appreciate what is often underground, out of sight and out of mind and saves our lives (clean water) in beautiful structures like Toronto's R.C.Harris filtration plan and Hamilton's first pump house?)
My Dillon team reunion 2018

A Woman's Place is in the... (engineering profession of course!)

Good or Good Enough (what is the role of innovation in our work, plus my experience on mega projects like Mary River Iron Mine on Baffin Island and the Windsor Essex Parkway P3, and the more local Regent Park Revitalization where we discuss stormwater vs energy sustainability)

Plangineers (our professional engineering and planning origin stories, including that toothpick bridge)

SEASON 1 PODCAST WEB LINKS (with show notes)

Power to the Sheeple

Like Millenials

The Day After Tomorrow

Dancing About Infrastructure

A Woman's Place is in the...

Good or Good Enough


STATIC LINKS (bonus material)

ArtWorkX blog post

Is the River Longing?

The Toothpick Bridge


And Season 2 Episode 1 is now online too! In Season 2 we break new ground with The People's (Food) Court and our guest Lesley Pavan, Director of Design and Development at the City of Mississauga shares her insights into the lifestyle choices on offer in the rapidly urbanizing city where she both works and lives.

download directly:

Data vs Cartoon Infographics? Ontario Extreme Rainfall Data Trends Show Increases and Decreases, Contradicting Environmental Commissioner of Ontario 2017 Report

ECO Report uses a cartoon call-out to explain climate change trends
in Ontario but fails to provide any data to support statements regarding
historical storm trends. Data tells a different story on storm trends.
The Environmental Commissioner of Ontario (ECO) has released her 2017 Greenhouse Gas Progress Report, Ontario’s Climate Act: From Plan to Progress, to the Ontario Legislature.

The report fails to acknowledge extreme rainfall trends in Ontario, ignoring trends identified by the academic community and fundamental information in the official Engineering Climate Datasets.

Chapter 9 indicates:

Here in Ontario we are already feeling the effects of climate change. Higher average temperatures, more climate extremes and the increased incidence of drought, storms, and unseasonable temperatures are affecting people across the province."

ECO has relied on cartoonish data previously in describing climate change issues, but the ECO infographics contradict engineering data used for infrastructure design and flood risk assessments. Toronto observed annual maximum rainfall trends have been decreasing for durations of 5 minutes to 24 hours.
Unfortunately, local data does not support ECO's stated increased incidence of storms. In fact Engineering Climate Datasets show twice as many statistically significant decreasing annual maximum rainfall trends as increasing ones - these are the observed, measured, documented data trends:

Ontario climate change
Short duration rainfall in southern Ontario shows many statistically decreases for duration of 2 hours or less and only one statistically significant increase. There are several statistically significant decreases for 5 to 15 minute durations but no increases for the shortest rainfall durations. 

The ECO report exercises an "Availability Bias" to characterize storm incidence stating "  The Toronto floods in 2013, the 2014 floods in Burlington and parts of eastern Ontario, and those experienced on the Toronto Islands, in Windsor, in Cambridge, in Minden and in the Ottawa-Gatineau region in 2017, are all the types of events that climate change makes more likely." Evidence-based policies should instead rely on data to characterize extreme weather risks as opposed to anecdotal lists.

July 8, 2013 was a record rainfall for July 8ths but
daily maximum rainfall has been decreasing.
Despite the fact Toronto experienced a flood in 2013, Toronto rainfall extremes have not increased. The chart at right shows that the 2013 maximum rainfall while above average is still part of a decreasing trend since the 1940's. Media report July 8, 2013 as a record .. which is true for all historical July 8ths - but nobody designs infrastructure for rainfall on particular calendar days. Too often, median and non-technical reports confuse the incidence of flooding with that of extreme rainfall - correlation is not the same as causation when it comes to rain and flooding, as urbanization has significantly increased flooding, despite clear stationary extreme rainfall trends.

Academic research published in the International Journal of Environmental Research, Changes in Rainfall Extremes in Ontario relies on data and peer-reviewed analysis to characterize extreme rain - that rigorous approach indicates no obvious regional pattern:

Many Ontario Extreme Rainfall Trends are decreasing especially in
south west and south east regions.
There is a general consensus that climate change has impact on the intensity and frequency of rainfall events. However, very little research is available about the changes in short term rainfall extremes. The focus of this paper has been on the change in annual and monthly rainfall extremes in Ontario. The results indicate a greater variability (increase and decrease) among stations for shorter durations (15-min, 30-min, and 60-min). There is no obvious regional pattern with possible exception of increasing trends at north-western locations."

The table from the paper below shows that Southwest Ontario and Southeast Ontario rainfall has been decreasing at many climate stations, including many statistically significant decreasing trends. Similar to the Environment and Climate Change Canada's Engineering Climate Datasets, there are more statistically significant deceases than increases.

Extreme rainfall trends in Ontario show decreases and increases.

Short Duration Frequent Rainfall Show No Change in Southern Ontario IDF Design Intensities - No Change in Averages Suggests No Change in Extremes

It is often stated that changes in average conditions are an indicator of changes in extreme conditions. This makes sense for rainfall statistics as a change in typical conditions, such as an increase in rainfall intensities, can be accompanied by higher extreme values as well (i.e., the whole distribution shifts). Since extreme values are somewhat elusive to those recording rainfall intensities at Canadian climate stations - that is, they are rare and may not be readily observed in short records or sparsely-spaced climate stations - we can look at the trends in the more abundant and frequent short duration rainfall statistics as an indicator of where the extreme values are heading.

The following table summarizes trends in short duration rainfall intensities for long term Southern Ontario climate stations (below latitude of 44 degrees). Stations have at least 30 years of record. The change in 2-year 5 minute rainfall intensity and 5-year 10 minute rainfall intensity have been calculated using a starting point of then Environment Canada's 1990 IDF tables (obtained from Environment and Climate Change Canada in 2017), and an ending point of the Version 2.3 Engineering Climate Datasets.

Climate change rainfall
Change in average and frequent rainfall intensities in southern Ontario.
The review indicates that there has been no increase in frequent short duration rainfall intensities. In fact the most frequent 2-year (i.e., average), 5-minute duration rainfall intensities have decreased somewhat. This is welcome news considering the potential for frequent storms to cause erosion in southern Ontario streams. This also suggests that extreme rainfall intensities have not changed as a result of the average rainfall intensities changing. That is, there is no consistent shift in the average rainfall intensities at long term climate stations.

The Insurance Bureau of Canada and the Institute for Catastrophic Loss Reduction have reported that average rainfall intensities have shifted by an entire standard deviation (thus making extreme 40 year storms become more frequent 6 year storms) - this has been refuted by Environment and Climate Change Canada (see Canadian Underwriter editor's note). The data in the above table indicate no such shift.

It is a commonly held belief that rainfall intensities have increased dramatically as a result of climate changes effects. Recently the Globe and Mail reported "It is hard to ignore the growing relationship between climate change and the resulting impact of severe flooding events." .. actually its hard to explain the role of changing climate given rainfall intensity data in some regions. It may be best to ignore rainfall and focus on other flood risk drivers like urbanization and intensification.

Datasets from Environment and Climate Change Canada refute the belief that rainfall is becoming more extreme.


The following tables show the 2 to 5 year IDF trends for 5 to 10 minutes (first table), and 5 to 10 year trends for 1 hour and 2 hours (second table)

1990 (pre-version 1) IDF Dataset Worksheets have been prepared for Ontario stations:
Ontario Disk 1 Volume Tables :
Ontario Disk 2 Volume Tables :
Ontario Disk 3 Volume Tables :
Ontario Disk 4 Volume Tables :

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 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