High Water Event – September 20, 2015

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High Water Event – September 20, 2015

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So how did this last high water measure up to past events?

Keep in mind that every high water event is different, influenced by many contributing factors. Temperature is a big factor- warm rain brings down accumulated snow pack and the river rises rapidly. During colder spells, it can rain heavily for days without much change in the river level- its mostly falling as snow throughout our watershed, which has a lot of high elevation. On Sept 20 we had 60 mm of rain but the temperature was 17- the river came up over 16 feet in 24 hours. Three days later we had over 40 mm or rain, but the temp was only 11 the river only rose about 6.

Historical comparisons to BIG floods:

On Sunday Sept 20, streamflows on the Squamish River near Brackendale were at 1790 m3/s., a flow rate that exceeds the five-year return period flow .

In recent years, we have seen similar high water events- 1995 (1660m3/s), 2001 (1530m3/s), 2006 (1610m3/s), 2010 (1700m3/s)

By contrast, the flood of 2003 saw streamflows of 3140 m3/s.

The most damaging floods (6 in the last 30 years) were over 2000m3/s If it had rained another day or so- the result could have been a LOT more severe.

Important considerations

  • Planning for animal care/evacuation to high ground/ feed and hay storage above grade
  • Protecting the water supply- wells get contaminated during prolonged floods
  • Because of the speed that we can expect future flooding events- its very likely to be stuck on the other side of th e reserve, with no way to get home- do you have a contingency plan?

Recorded Peak Discharges from 1958- 2012

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Historical overview of Max and Min discharges between 1981 and 2012 (highlighting 2003 in red)

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Gallery

Ellie Scott
Ellie Scott
Lived in the valley for 20 years! Still think its a magical spot-- we have a special place with lots of great neighbours, hoping we can keep that sense of neighbourhood going!

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