Tuesday, July 9, 2013

The worst thing Toronto can do next with flood information


Some people think I get a little too ahead of myself when it comes to spotting potential issues.  On June 24th this year, I pointed out a jarring issue with Canada's "1 in 100 year" flood planning information that it provides to the public.  In short, I pointed out that it's dumbed-down, retroactive-looking, "cherry-picked" information that uses the data that they want to use, to paint an inaccurate story - because the truth would cause the city a bigger issue where people don't want to live here.  

The main issue, that I pointed out, was that the known rainfall potential for the area and it's subsequent flooding is projected to be higher than the actual retroactive-looking models the city currently bases everything political and financially on.

In other words, the city is in denial.  

Now it's just over two weeks later, and what I previously said could happen, already has.  Last nights storm beat the previous "regulatory event".   The worst possible thing that can happen now, is the city makes last night's storm the new regulatory worst case scenario.  

Here's why:
  1. We had 74mm rain in one hour.  But it could have rained for 90 minutes or even 3 hours at that rate.
  2. What happens if we next have three days in a row with a further 30mm of rain per day landing on this already water-logged soil?  If it cannot drain into the ground then it becomes a compounding issue, even though it's not very heavy rainfall.

It doesn't take a genius to ask the question as to where does it go next?  The answer is up.  It sits on the soil, it sits in higher water-tables, it raises rivers, it goes to above ground flood-plains and so forth.

In conclusion, the city really must not use yesterday as the new "regulatory event".  It needs to look forward 20 or 30 years and use the already predicted data.  

Until the city does that, what I said previously should still stand:  Whatever the city sets the flood plain information at, don't believe them.  Double it at least, instead.