Canadian Dam Association Bulletin - Fall 2017 - 44

Ouranos Press
Release - 2017 Spring
Floods in Quebec

Communiqué
Ouranos - Inondations du
printemps 2017 au Québec

H

ydro-climatic hazards are among the most frequent
and significant natural disasters in Quebec. The
exceptional floods of 2017 have caused considerable
damage and raise questions about the impact of climate change
on the recurrence of such events.
According to the analyses of the Ministry of Sustainable
Development, Environment and Climate Change (MDDELCC)1,
"The year 2017 was characterized in southern Quebec
by a cold season (December to May) that, on average,
ended with a lot of snow (262 cm, 125%) and rain (223
mm, 138%), resulting from a snowy (180 cm, 125%) and
mild (+2.3 °C warmer) early winter climate (December to
February). This was followed by a rainy (193 mm, 144%),
snowy (73 mm, 120%), and cool (0.7 °C cooler) spring climate (March to May). Beginning in April with the melting of nearly half of the heavy snowpack on the ground,
significant rains fueled a historic spring runoff, causing
flooding in several areas. Since the still thick and water
saturated snow cover remained until May, consequences
ensued. Finally, this late melt was accompanied by heavy
rains, where the average rainfall was estimated at 425 mm
over southern Quebec, which is the second-largest event
in the past 55 years during spring melt. Nearly half (206
mm) of this rainfall occurred quickly in the first two weeks
of May, causing flooding in more than half of the administrative regions. Some rivers in the west of the province
have exceeded their historical peak flow and flooding has
been observed in most regions. It can therefore be stated
that the floods of 2017 correspond to a rare event likely to
occur about once every 50 to 100 years (Ouranos)."
From the point of view of climate change, it remains difficult
to link an extreme weather event to climate change. According
to experts from the Ouranos network 2,
"The flood of May 2017 does not appear to bear a signature specific to the anticipated climate change, since on
average, spring floods are not expected to become more
significant in the future in southern Québec, particularly
because of lower expected snow accumulation during the
winter. On the other hand, it is important to remember
that extreme weather events, including exceptional spring
floods, can still occur in the future when conditions (snow,
rain, and temperatures) are met, as was the case this year.
Climate change is expected to produce more flash floods
in small areas as a result of violent storm events, particularly in summer."
Climate researchers say global warming will affect the
frequency and severity of hydrometeorological extremes.
Globally, warmer temperatures increase evaporation and
the amount of moisture stored in the atmosphere, leading to
the occurrence of extreme weather events causing flooding.
Nevertheless, on a finer scale, the evolution of the flooding risk has both physical and anthropogenic dimensions,
linked in particular to land-use planning, making the overall
continued on page 45

44

L

es aléas hydro-climatiques figurent parmi les catastrophes naturelles les plus fréquentes et importantes
pour le Québec. Les inondations exceptionnelles de 2017
ont engendré des dommages considérables et soulèvent des
questions quant à l'impact des changements climatiques sur
la récurrence de tels événements.
Selon les analyses du Ministère du Développement durable,
de l'Environnement et de Lutte contre les Changements
Climatiques (MDDELCC)1,
« l'année 2017 fut marquée par une saison froide (décembre à
mai) s'étant terminée avec beaucoup de neige (262 cm, 125 %) et
de pluie (223 mm, 138 %), en moyenne dans le sud du Québec,
résultat d'un hiver climatologique (décembre à février) neigeux
(180 cm, 125 %) et doux (anomalie de 2,3 °C), suivi d'un printemps climatologique (mars à mai) pluvieux (193 mm, 144 %),
neigeux (73 mm, 120 %) et frais (anomalie de -0,7 °C). Des pluies importantes ont alimenté une crue printanière historique
causant des débordements dans plusieurs régions, qui s'est
amorcée en avril avec la fonte de près de la moitié de l'important couvert de neige au sol. Le couvert de neige étant tout
de même demeuré épais et gorgé d'eau jusqu'au mois de mai,
les répercussions ont perduré. En somme, cette fonte tardive a
été accompagnée de pluies abondantes où l'on estime l'apport
en eau à une moyenne de 425 mm sur le sud du Québec, ce
qui représente le deuxième plus important des 55 dernières
années en période de fonte. Près de la moitié (206 mm) de
cet apport est survenu rapidement, lors des deux premières
semaines de mai, causant des inondations dans plus d'une
région administrative sur deux. Certaines rivières de l'ouest de
la province ont dépassé leur débit maximal historique et des
débordements ont été observés dans la plupart des régions. On
peut donc affirmer que les inondations de 2017 correspondent
à un événement rare susceptible de se produire environ une
fois à tous les 50 à 100 ans (Ouranos) ».
Du point de vue des changements climatiques, il demeure
difficile de relier un événement météorologique jugé extrême
aux changements climatiques. Selon des experts du réseau
d'Ouranos2,
« la crue de mai 2017 ne semble pas porter une signature
propre aux changements climatiques anticipés, puisqu'en
moyenne, il n'est pas attendu dans le futur que les crues
printanières deviennent plus importantes dans le sud du
Québec notamment en raison d'une plus faible accumulation
de neige durant l'hiver. Par contre, il est important de rappeler
que les événements climatiques extrêmes, dont les crues
printanières exceptionnelles, pourront aussi se produire dans
le futur lorsque les conditions (neige, pluie et températures)
seront réunies, comme c'est le cas cette année. Par ailleurs,
l'évolution du climat pourrait produire davantage de crues
éclair sur de petits territoires, résultat d'événements orageux
violents, et ce particulièrement en été ».
Les chercheurs dans le domaine du climat affirment que le
réchauffement global de la planète affectera la fréquence et la
suite à la page 45

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Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Fall 2017

Board of Directors
President’s Message
2018 Board of Directors Update
2017 CDA Awards
Screening Level Risk Assessment for a Portfolio of Tailings Dams
Dam Safety Review, Public Safety Workshops Hit the Road
CDA Events Photospread
Gardiner Dam 50th Anniversary
Jim’s Journey – Memoirs by Jim Gordon
CDA Launches Digital Editions of Guidelines
Invitation From Icold 2018 in Vienna
Icold Corner
Notice of the Annual General Meeting
Ouranos Press Release – 2017 Spring Floods in Quebec
CDA Young Professionals
CDA 2018 Conference
Time to Renew Your Membership
CDA News Brief
Buyers’ Guide and Trade List
Canadian Dam Association Bulletin - Fall 2017 - Intro
Canadian Dam Association Bulletin - Fall 2017 - cover1
Canadian Dam Association Bulletin - Fall 2017 - cover2
Canadian Dam Association Bulletin - Fall 2017 - 3
Canadian Dam Association Bulletin - Fall 2017 - 4
Canadian Dam Association Bulletin - Fall 2017 - 5
Canadian Dam Association Bulletin - Fall 2017 - 6
Canadian Dam Association Bulletin - Fall 2017 - Board of Directors
Canadian Dam Association Bulletin - Fall 2017 - 8
Canadian Dam Association Bulletin - Fall 2017 - President’s Message
Canadian Dam Association Bulletin - Fall 2017 - 10
Canadian Dam Association Bulletin - Fall 2017 - 11
Canadian Dam Association Bulletin - Fall 2017 - 12
Canadian Dam Association Bulletin - Fall 2017 - 13
Canadian Dam Association Bulletin - Fall 2017 - 2018 Board of Directors Update
Canadian Dam Association Bulletin - Fall 2017 - 2017 CDA Awards
Canadian Dam Association Bulletin - Fall 2017 - Screening Level Risk Assessment for a Portfolio of Tailings Dams
Canadian Dam Association Bulletin - Fall 2017 - 17
Canadian Dam Association Bulletin - Fall 2017 - 18
Canadian Dam Association Bulletin - Fall 2017 - 19
Canadian Dam Association Bulletin - Fall 2017 - 20
Canadian Dam Association Bulletin - Fall 2017 - 21
Canadian Dam Association Bulletin - Fall 2017 - 22
Canadian Dam Association Bulletin - Fall 2017 - 23
Canadian Dam Association Bulletin - Fall 2017 - 24
Canadian Dam Association Bulletin - Fall 2017 - 25
Canadian Dam Association Bulletin - Fall 2017 - 26
Canadian Dam Association Bulletin - Fall 2017 - 27
Canadian Dam Association Bulletin - Fall 2017 - 28
Canadian Dam Association Bulletin - Fall 2017 - 29
Canadian Dam Association Bulletin - Fall 2017 - Dam Safety Review, Public Safety Workshops Hit the Road
Canadian Dam Association Bulletin - Fall 2017 - 31
Canadian Dam Association Bulletin - Fall 2017 - 32
Canadian Dam Association Bulletin - Fall 2017 - 33
Canadian Dam Association Bulletin - Fall 2017 - CDA Events Photospread
Canadian Dam Association Bulletin - Fall 2017 - Gardiner Dam 50th Anniversary
Canadian Dam Association Bulletin - Fall 2017 - 36
Canadian Dam Association Bulletin - Fall 2017 - 37
Canadian Dam Association Bulletin - Fall 2017 - Jim’s Journey – Memoirs by Jim Gordon
Canadian Dam Association Bulletin - Fall 2017 - CDA Launches Digital Editions of Guidelines
Canadian Dam Association Bulletin - Fall 2017 - Invitation From Icold 2018 in Vienna
Canadian Dam Association Bulletin - Fall 2017 - Icold Corner
Canadian Dam Association Bulletin - Fall 2017 - 42
Canadian Dam Association Bulletin - Fall 2017 - Notice of the Annual General Meeting
Canadian Dam Association Bulletin - Fall 2017 - Ouranos Press Release – 2017 Spring Floods in Quebec
Canadian Dam Association Bulletin - Fall 2017 - 45
Canadian Dam Association Bulletin - Fall 2017 - CDA Young Professionals
Canadian Dam Association Bulletin - Fall 2017 - 47
Canadian Dam Association Bulletin - Fall 2017 - CDA 2018 Conference
Canadian Dam Association Bulletin - Fall 2017 - 49
Canadian Dam Association Bulletin - Fall 2017 - Time to Renew Your Membership
Canadian Dam Association Bulletin - Fall 2017 - CDA News Brief
Canadian Dam Association Bulletin - Fall 2017 - 52
Canadian Dam Association Bulletin - Fall 2017 - 53
Canadian Dam Association Bulletin - Fall 2017 - Buyers’ Guide and Trade List
Canadian Dam Association Bulletin - Fall 2017 - cover3
Canadian Dam Association Bulletin - Fall 2017 - cover4
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