Letter to the editor 1, May 2, 2019
Protection versus augmentation
Dear Editor, I would like to review a few pertinent questions regarding the flooding this year and in 2017. 1. What caused the flood? 2. How can future floods be prevented? The easy answer is to blame the floods on climate change but I think we should look a little deeper. Every year in April, river levels rise. This is mainly attributable to snow melt and excessive rainfall which falls on frozen ground and cannot be absorbed.
The average rainfall in Montreal for April is about 70mm. In 2017 it was about 110mm and so far this year April has brought the same amount of rain at about 110mm. So you may say there's been a lot of rain, but actually last year rainfall in April was also over 100 mm and there were no floods. This means that a fast snow melt may be the major factor to raising water levels. The average winter snowfall in Montreal is just over two metres and we've had a bit more than that this year and the same is true for Mt Tremblant where they've had the most snow for 20 years. So I assume that the snow depth in the countryside was deeper than usual this year... it certainly was in my back yard!
As we know that most of the accumulated snow melts in April, what measures are taken to reduce the water levels in all the reservoirs behind the hydro-power dams in March? Is this being managed in a competent way? Are snow depths being carefully monitored and reservoir water levels being adjusted accordingly? Management of reservoirs such as the Ottawa River is a compromise between 'low flow augmentation'
and 'flood protection.' The government of Canada says, "An operational (computer) model is used for the Ottawa River basin to determine flow releases from the 13 major reservoirs in the system."
Perhaps this model needs a few tweaks. I think the emphasis should be a little more on 'flood protection' rather than 'low flow augmentation' to prevent a re-occurrence of disastrous floods in the years to come. I am sure a lot of folks who have lost their homes would agree with me and would like to question the water managers more closely. Chris Crouch Vaudreuil-Dorion