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By the numbers: The 2013 Toronto Flood

Posted by Chris Bateman / July 10, 2013

Toronto flood 2013Now that the worst of the water has drained away and the city's infrastructure is (almost) back to normal, now seems like a good time to take stock of Toronto's biggest ever rain event. In the minutes after the surprise deluge began, thousands of buildings went dark, the subway ground to a halt, and major highways, local roads, and underpasses disappeared beneath the murky brown water - all in time for the evening rush-hour.

Using the data that's currently available (there's still a lot of tallying going on) it's possible to get a sense of the storm and its effects. The fact that there were very few injuries is a symbol of the lessons learned from Hurricane Hazel, Toronto's deadliest natural disaster made worse by poor city planning.

toronto floodThe sheer amount of rain that fell on the Toronto is absolutely staggering. Using precipitation figures for downtown and the number of square metres in the city limits, it's possible to estimate around 61,110,000,000 (61.1 billion) litres of liquid fell from the sky. By comparison, the Rogers Centre, closed and filled to the top of its domed roof, would only hold 1,600,000,000 (1.6 billion) litres.

A giant would need to use the stadium as a bucket (and the roof as a cup) 38 times to bail out all of the rain were it gathered into a single sprawling lake. That body of water, by the way, could cover an area of 630 square kilometres to a very shallow depth.

toronto floodAt the peak of the deluge around 300,000 Toronto Hydro customers were without power, almost a third of its 709,000 subscribers. It's important to note the term "customers" doesn't equal people: an apartment building and family home both represent just one subscriber, the company says.

toronto floodThe outage also affected the TTC, particularly underground. 5 separate closures snarled subway network and left 37 of 69 stations without service. Just 65 shuttle buses made avoiding the chaos practically impossible.

Also on the rails, a Richmond Hill bound GO train became trapped just south of Pottery Road amid rising Don River flood waters. 1,400 people (and 1 Northern water snake) were on board by the transit agency's estimate.

toronto floodIn terms of calls for help, the city's non-emergency 311 line received more than 1,000 notices about flooded basements. Figures aren't yet available for 911 calls, though emergency services said they experienced a high volume of requests for help.

It's tough at this stage to put a dollar figure on the damage. The latest estimate pegs it at well above the $600 million clean-up cost from the 2005 tornado. In unusual losses, a high-flying employment lawyer's Ferrari became swamped in the Dufferin underpass and inspired a fake Craigslist ad.

As a bonus feature, here's a look at the rain for the entire GTA (the graph above is only for Toronto) compared with the Rogers Centre capacity. Yikes.

toronto flood

Chris Bateman is a staff writer at blogTO. Follow him on Twitter at @chrisbateman.

Photo by Tom Ryaboi



J / July 10, 2013 at 12:44 pm
These are some of the worst graphics I've ever seen
Why so Blue / July 10, 2013 at 12:46 pm
Wow, someone hates circles.
submerged / July 10, 2013 at 01:10 pm
There were kids on Lakeshore (Lakeshore / Bathurst) area that were posing, jumping, splashing and laying in the brown, murky water. It was pretty gross. Thankfully no one was drowning in this harrowing experience.

I was crying and rocking myself thinking the end was near! :(
Ford really let us down / July 10, 2013 at 01:15 pm
He's been in office for three years, and supposedly cares about infrastructure and the little guy, and yet has systematically nickeled and dimed infrastructure at every juncture, not to mention the missed opportunity for THOUSANDS of good-paying construction jobs for citizens.

Ford has been in office for THREE years and even after this massive storm, he STILL doesn't have a clue what to do or what we should waste precious tax dollars on it.

We're DROWNING here, Mayor Ford...WAKE UP!
Jason / July 10, 2013 at 01:16 pm
I think comparing hypothetically fluid-filled buildings with actual fluid-filled topography makes for an excellent mental disconnect.

Swimming pools maybe?
RKMK / July 10, 2013 at 01:31 pm
It's SkyDome, you corporate shills.
Theo Von Milosevic / July 10, 2013 at 01:34 pm
I have a small private aquatic petting zoo which I had maintained in the west end of Toronto. During this horrific storm my tanks overflowed and I lost 13 of my 20 sea otters and my prized walrus named Smooshi, who I rescued last year from horrific conditions at marine land. My heart weeps for my lost pets, but really best friends. All I can do is pray that they are safe and that they are returned to me soon. :( Damn you storm, DAMN YOU!!!
W. K. Lis / July 10, 2013 at 01:40 pm
Monday's rainfall was a record for Pearson Airport. However, other parts of Toronto received more rain during Hurricane Hazel (over 200 mm) than even that amount.

Nonetheless, there could have been more water being drained by rivers, streams, sewers, and valleys. There is more parking lots, wide highways, roofs, and streets that does not allow the rain to filter into the groundwater. Instead, it just adds more water to the runoff.
KT replying to a comment from Theo Von Milosevic / July 10, 2013 at 01:43 pm
Wow! hope you'r going to find them soon. You should go to the press with your story. They can probably help you.
Steven / July 10, 2013 at 01:51 pm
Don't blame the infrastructure when there's a flash flood.

The storm of that magnitude is rare, thankfuly.
Phil Demers replying to a comment from Theo Von Milosevic / July 10, 2013 at 01:57 pm
You're joking, right? I assume you must be. However, I don't get the joke.
McRib replying to a comment from KT / July 10, 2013 at 02:05 pm
i think Theo is pulling your leg ;-)
poopH20 replying to a comment from submerged / July 10, 2013 at 02:08 pm
Probably those kids from the co-ops down there.

Wouldnt expect anything less but for them to be flailing around in that water.
Moneesha replying to a comment from Theo Von Milosevic / July 10, 2013 at 02:09 pm
Good one!
Moneesha replying to a comment from Ford really let us down / July 10, 2013 at 02:09 pm
Yes, I suppose he could have legislated for it not to rain.
matts / July 10, 2013 at 02:39 pm
Is this correct? Seems incredibly high: "The bill Metrolinx received from the city for conducting the seven-hour rescue - $150 million"
Mike / July 10, 2013 at 02:53 pm
We don't design infrastructure to handle storms that large. The storm we received has a probability of occurring once every hundred years or so. Definitely some areas flooded that shouldn't have (like basements) but flooding on the DVP or underneath the railway overpass on king street is not unexpected.

Now, if storms like this become the new normal due to climate change then we have a bigger problem. Time will tell if that's the case but if it is then the solution won't be a matter of bigger pipes in the ground. It will involve a total rethink around the way we build cities.
Mark / July 10, 2013 at 03:47 pm
I doubt that is the real number but that $150 million billed to metrolinx would just about equal the amount the province is taking back from Toronto. One way to get our money back I guess.
Brenda / July 10, 2013 at 08:10 pm
I wish Mel was still our mayor!
Bo Jangles / July 10, 2013 at 10:26 pm
What's the source the Metrolinx bill came from? I haven't read that elsewhere. $150MM seems outrageously inflated. I'd like see supporting detail around that number.
Tom / July 11, 2013 at 09:55 am
The storm we got was more than a 100 yr storm. This is the Intensity-Duration chart for a 100 yr storm for Pearson. The chart shows the Total length of the storm, and the amount of rain that has to fall during that time for it to be a 100 yr storm. (a 5 minute cloudburst that drops 18.7 mm and one day's worth of steady 4.7 mm/hr rainfall are both 100 yr storms)

5 min 18.7 mm
10 min 27.3 mm
15 min 34.3 mm
30 min 45.5 mm
1 hr 51.3 mm
2 hr 61.6 mm
6 hr 84.4 mm
12 hr 99.1 mm
24 hr 113.4 mm

For a 6 hr storm, 84.4 mm makes it a 100 yr storm. Pearson got 120mm
Actuarian / July 11, 2013 at 10:00 am
1. I don't get the graph. There are two possible interpretations, yielding the following ratios of the radius of the blue circle to the radius of the black circle. The first assumes the area occupied by the circle is proportional to the volume of rainfall: (61,110/1,600)^(1/2) = 38.2^0.5 = 6.2. Alternatively, the circles could be spheres filled with water: (61,110/1,600)^(1/3) = 3.4. Instead, the blue area has a radius 22 times that of the black area. Why?
2. "a very shallow depth" is ambiguous until you do the math and determine that in this case it is arbitrarily 9.7cm. It could as easily be 1 cm (6,110 square kilometres) or 1 m (61.1 square kilometres).

The above issues considered, how can the raw numbers presented themselves even be trusted?
Actuarian replying to a comment from Actuarian / July 11, 2013 at 10:07 am
Oh yeah, the TTC shut down graph is very strange too. Did anyone peer review this before it went out?
Mary / July 12, 2013 at 05:45 am
I'm pretty sure that 300,000 is more than "almost a third" of 709,000.
Kids Clothes / September 15, 2013 at 07:24 pm
You can tell whether the elastic is too tight by giving it a small tug to see how much it expands.

There are all types of clothing articles for boys as well as girls right online.
They are inexpensive, easy to clean up and are good for painting
large projects. Shiloh Jolie-Pitt looks like a boy with Tomboy style.
Mel Dawn / May 29, 2014 at 10:17 pm
Kind of sad.
Mel Dawn / May 29, 2014 at 10:18 pm
This also makes me wonder what everyone happened to the "hydro rebates gta" plan? I guess it's up to us to make our own homes power worthy!
Rob M / March 19, 2016 at 08:44 am
"Ford really let us down" said "Ford has been in office for THREE years and even after this massive storm, he STILL doesn't have a clue what to do or what we should waste precious tax dollars on it."

The basement flood remediation program in Toronto is actually funded by the water rate (a proportion of your water bill), not taxes.

Toronto Water is doubling efforts on sewer capacity upgrades and that will be reflected in the water rate.

The City will prioritize upgrades and if the cost is less than $32,000 per benefiting property owner, then project will move ahead to detailed design and implementation.
Rob M / March 19, 2016 at 09:25 am
Author should qualify "Toronto's biggest ever rain event" and critically review the flood impacts since in the Don River watershed there was NOT a record rainfall, and the resulting flow rate of 180 cubic metres per second was pretty low - less than a 5-year flood flow (only 213 cms per TRCA's Don Watershed Plan Hydrology/Hydraulics Report 2009, page 10). Here are more details on that fact:

The real story about the Richmond Hill GO Train is that there was a LARGER FLOOD WEEKS BEFORE. The July 8, 2013 flood in Don River was not uncommon. and Metrolinx did not have a plan to identify or manage risks on a rail line whose flood risk has been documented for DECADES in perhaps the most studied and real-time-monitored watershed in Canada.

Record rainfalls occurred in the adjacent watersheds (Etobicoke Creek, Mimico Creek, Humber River) but not in The Don River - that is not unlike the Hurricane Hazel patterns that spared central and eastern Toronto.

The GO Train tracks at the flood site are BELOW the 2-year river flood level, so how is this news besides highlighting the rail operator's incompetency in the face of a known hazard? TRCA records show flood levels reached the rail elevation on August 4, 2014, on October 28, 2015 .... on and on it goes.

The premise of the article is to WOW everyone with numbers and charts. A greater service would be to look into the facts behind the near tragedy and the those pursuing measures that should be taken to reduce known risks in the future. The rainfall in litres chart is supposed to make us think its a big storm, when in fact the Don Watershed was not hit hard at all, risks were known and pretty reckless actions by the rail operator caused a near tragedy - water levels were rising rapidly when the train departed Union Station.

The flooded Ferrari pays into heuristic biases in reporting about rainfall and climate and ignores that fact that underpasses ARE DESIGNED TO FLOOD - Yes, sags in the landscape accumulate water and pipes underneath only have low slopes to drain away to. But what is the lead picture?: flooded underpass sag. Here's are few more heuristic biases in the context of rain and flooding to keep your eye on for the next extreme weather report where attention-grabbing stats are needed:

And here are some facts on extreme weather trends that everyone should get familiar with (storms are not increasing) as they prepare to pay out for cap and trade in Ontario and a way to stop climate change and flooding (not true):

(and methinks the Pearson Airport rain gauge with record rainfall is in Mississauga not Toronto? hmmmmmm ?)
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