Showing posts with label rainfall records. Show all posts
Showing posts with label rainfall records. Show all posts

Annual Maximum Rainfall Trends in Canada - Engineering Climate Datasets v3.00 and 2.30 Comparison

This blog has reviewed annual maximum rainfall series trends in the past, including all the v2.30 Engineering Climate Dataset trends across Canada.  Also v3.00 trends for stations with long term records and southern Ontario derived IDF trends for long-term stations.

Overall most trends are not statistically significant and the few percentage of significant increases and decreases can be explained largely by chance.  The follow charts compare the trends for all Environment and Climate Change Canada's Canadian stations using the v2.30 data and the newest v3.00 data release in winter 2019.

Maximum rainfall trends in Canada.  Environment and Climate Change Canada's Engineering Climate Datasets.
What do the charts show? Not much change after adding 15% more stations and up to 10 years more data. The following tables illustrate the percentages of significant ups and downs (red and green bars), non-significant changes (the grey bars) and no data (not shown in the charts).

Maximum rainfall trends in Canada - Direction and Statistical Significance.  Environment and Climate Change Canada's Engineering Climate Datasets v2.30 and v3.00 Comparison.
The data show that in v2.30 over 86% of trends were not significant. In v3.00 a bit fewer statistics were non-significant.  The increase in statistically significantly trends was 0.09%.  The increase insignificantly significant decreases was 0.03%.  These are essentially zero changes.

Nationally, there are more significant increases than decreases. Some regions, however have trends that go against these averages.  In southern Ontario, there are a few more decreases than increases, but twice as many statistically significant decreases than increases:


  • Decreasing annual maximum rainfall volumes over all durations 5 minutes - 24 hours   = 43.4%
  • Zero trend in annual maximum rainfall volumes over all durations 5 minutes - 24 hours =   4.3%
  • Increasing annual maximum rainfall volumes over all durations 5 minutes - 24 hours     = 42.1%
  • Number of statistically significant decreases = 12
  • Number of statistically significant increases = 6






  • Radical Transparency. Uncovering the 'big secrets' in urban flood risk adaptation and extreme rainfall trends under climate change in Southern Ontario.

    "Truth and untruth exist at the same level of authority on the internet."
    Salman Rushdie, on Fareed Zakaria GPS, September 17, 2017

    "Only the small secrets need to be protected. The big ones are kept secret by public incredulity."
    Marshall McLuhan

    Too bad. Lets expose the big secrets in flood risk management and climate adaptation, and give truth the upper hand, shall we?

    Lets encourage "radical transparently". Why? So that we can create data-driven, evidence-based policies to cost-effectively manage flood damages and reduce risks to people and property.

    This radical transparency is promoted by Ray Dalio, founder of Bridgewater Associates (see his Ted Talk here on successful investing and company building). Dalio says that to be successful we need to "bet against the consensus" and "be right".

    The presentation below on the key drivers for managing flood risk in Southern Ontario goes against the consensus in terms of extreme weather extremes (showing they are down not up) - but its not a bet, but rather a careful review of data - so in that regard I trust it is 'right' .... or certainly right-enough for its intended purpose given all the other uncertainties in hydrology and hydraulic disciplines.




    Ray Dalio in his Ted Talk shares his painful "Fail Forward" moment of ruin and how he used the experience to improve his decision making. He said "Rather than thinking 'I'm Right', I started asking myself 'How do I know I'm Right?' I gained a humility I needed in order to balance with my audacity. I wanted to find the smartest people who would disagree with me to try to understand their persepctive or to have them stress test my perspective. I wanted to create an idea meritocracy ..."

    Let me know your thoughts. I welcome any 'stress test' of my OWWA WEAO Joint Climate Change Committee presentation above. Thank you so much!

    R. Muir