One year ago today, on 7 July 2013, Toronto broke its single-day rainfall record with a total of 126mm recorded at Pearson Airport. Ninety-six of those millimetres of rain fell on the city itself. When was the broken record set? On 15 October 1954 when 121 mm of rain fell in a single day, in the form of Hurricane Hazel.
The enduring image of last summer's storm and the associated floods is the GO train to Richmond Hill, stranded in the water-logged Don Valley. It took seven hours to rescue all 1,400 passengers (and one distressed snake....), leaving the last people to escape after midnight. The police and other rescue services had to ferry individuals the short distance from the train to dry land over the fast-filling ditch in rafts pulled by cables. Some people couldn't stand the wait and climbed out of the train themselves and waded to safety. However, downed power lines and other hidden dangers made this an inadvisable move.
At the time, the news media and civic activists were worried about the impact on Toronto Hydro's resources. By the next day, swathes of the city were still without power in a nasty taste of what was to come with December's ice storm.
Although some southbound drivers on the Don Valley Parkway were caught by surprise when the river water started pouring over the road and they had to reverse and drive back the way they'd come, the flooding was actually to be expected. In spite of Toronto's post-Hazel plan to protect our rivers' floodplains, construction began on the DVP, which traverses the Don River's floodplain, just a few years after the hurricane. In other words, the Don Valley has always flooded and it always will, road or no road. In fact, artificial surfaces like the asphalt of the road, make the flooding worse because rain water is not absorbed as efficiently.
Flooding in this area is like to happen more often in the future as our rainfall increases in intensity with climate change. At the end of An Inconvenient Truth, Al Gore predicts that Ontario will become more tropical and we're starting to see this. We don't yet have a monsoon season, but it's probably a good idea to stay out of the Don Valley when heavy rains are expected.
If you look carefully at the photo with this post, you can see the stranded GO train just to the right of the salt beehive. The train had been there for quite a while when I took this picture. What you can't see, because they aren't there yet, are the emergency services. It took hours for the rescue to be organised. A warning system and a specific disaster plan for the area will go a long to to preventing this particular situation from being repeated this summer.