Nearly 200 cm of snow has fallen in the London area so far this winter —and much of it has stuck around because there’s been few warm days. Dale Carruthers reports on what conservation authority staff are doing to monitor the threat of major flooding that hasn’t been seen since 2008.
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Though winter weary-Londoners are impatiently awaiting spring’s arrival, officials worry a thaw could spell trouble along the Thames River.
The accumulation of snow near the Thames watershed could send an estimated 75 mm of water — around a month’s worth of precipitation — flowing into the river, raising fears of a repeat of the 2008 flood that swelled the Thames to its highest level in three decades.
“We haven’t seen a consistent snowpack like this for quite a few years,” said Steve Sauder of the Upper Thames River Conservation Authority.
“This year we haven’t really had the melt we’ve had in other years, so the amount of water content just keeps increasing as the year goes along.”
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WE ASKED . . .
Why is there so much snow?
London has been hit with more than its usual share of snow this year. There have also been just nine days this year when the mercury has risen above freezing, allowing the snow to pile up.
How does the conservation authority measure snowpack?
Staff take snow samples twice a month at 13 locations across the Thames River watershed.
Why is snowpack measured?
Measuring it gives officials an idea of how much water could melt into the river during the winter or early spring. The information is used for flood forecasting and reservoir management.
So is there going to be a spring flood?
It’s still too early to tell and depends on a combination of factors, including how fast temperatures rise, whether it stays warm overnight and how much rain falls in how short of a time.
What can be done to prevent flooding?
In anticipation of a heavy rain or melt, adjustments can be made at three major dams — Fanshawe, Wildwood and Pittock — to slow the downstream flow of water through major urban areas. There’s also a dyke system, like the west London dyke that protects about 1,100 homes near Labatt Park.
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BY THE NUMBERS
193 cm — Snowfall this winter
50-75 mm — Amount of water snowpack is holding
134 cm — Average year-to-date snowfall
9 — Days temperature his risen above freezing this year
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April 2008 flood
- Melting snow and heavy rain swelled the Thames to levels not seen since 1977.
- Harris, Gibbons and Thames parks were submerged.
- Flooding closed county roads.
- Two parking lots at Western University left underwater.