Current Connections

Understanding flow in the Elk River - the second Current Connections column of the season.

An aerial shot of the Elk River.

To understand the Elk River’s flood potential, look upstream. Actually, look past the stream entirely and look at the entire watershed and its history. The Elk Valley’s steep U-shape was carved out by a glacier that retreated 11,000 years ago. This glacier deposited sediment lining the ground surface in the valley bottom that restricts the downward flow of water and forces water to travel primarily as surface runoff. This means that, in instances of high water, streams and rivers will have a flashier response as less water is being held in the soil.

The Elk River is a gravel bed or a ‘free stone’ river, comprised largely of gravel, pebbles, cobbles and boulders, all greater than 2 mm in diameter, pulled by gravity from the steep tributaries and headwaters of the Elk watershed. When extreme floods occur, the bed structure is dismantled and gravels are transported downstream, changing the channel morphology. As a result, the shape and width of the Elk River is constantly changing with every flood event.

Recent and ongoing disturbances also affect streamflow. While often seen as destructive, disturbances like floods are a normal, cyclical part of ecosystems. Floods bring an influx of nutrients and sediment into the floodplain. This is similar to how forests go through a process of aging, disturbance, and renewal, essential for maintaining biodiversity and complexity.

Natural disturbances (beetle infestations and forest fires) as well as human-caused disturbances (forestry, mining and urbanization) affect streamflow and flood potential. When trees are removed, forest cover is reduced. With less snow and rainfall being intercepted, more will runoff onto the ground.  Lack of shade from trees increases the rate of snowmelt, causing earlier spring melt. Greater amounts of water from a faster spring thaw, combined with the limited space for groundwater due to the glacial till, is a recipe for more intense, earlier and rapid peak streamflows.

Streamflow typically peaks between mid-May to mid-June, while the rest of the season sees steady, low flow rates.  These high flows are usually harmless, but some years they turn into large floods that destroy critical infrastructure and threaten people’s homes. This begs the question: why some years and not others?

Snow pack has a lot to do with it, as peak snowmelt drives peak streamflow. It is extreme weather events that are the driving force behind flooding in the Elk Valley. Timing is everything!  If a particularly heavy rainfall occurs at peak snowmelt, the large input of water can drive a significant amount of overland flow with a very fast response in the river. Rainstorms are not the only kind of extreme weather that can drive floods, however, as the third largest flood recorded June 7, 1974 did not follow a heavy rainfall, but instead saw extremely high temperatures the week preceding the flood combined with a large snowpack.

From the Elk River Flood Strategy research, one of the main concerns with flooding in the Elk Valley is that the baseflows are increasing. There is evidence to suggest that the total May-June rainfall in Fernie and Sparwood is increasing and so might the number of large storms that could instigate a flood at this time. There is also some indication that there may be greater snow in the headwaters of the Elk River by May 1 of any given year. Given that most climate scientists suggest that greater weather extremes are likely to increase in frequency, this could mean more frequent flooding in the Elk Valley.

To find out more about the human-induced effects of floods and what you can do to protect yourself, stay tuned for upcoming Elk River Current articles.

 

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

TFA celebrates Valentine’s Day with Hearts and Treats assembly

Students sang, danced, and recited poems for Valentine’s Day, The Fernie Academy way

Local girl skates her way to BC Winter Games

Thirteen-year-old Bree Chardonnens will be representing the Kootenay region at the games

Fernie Seniors Centre offers support to Angel Flight

On February 13, Jim Booth, president of the Fernie Seniors Centre and… Continue reading

Fernie novelist launches third book with a party

Matt Clarke celebrates the completion of his third self published novel, The Dark Reflection.

Winner takes home snowboard in annual Rock Paper Scissors competition

Jordan Tostevin, a visitor from the United Kingdom won this year’s competition

VIDEO: Illicit drug overdoses killed 981 in B.C. in 2019, down 38%

Chief coroner says figures were down about a third in the province’s fourth year of the opioid crisis

VIDEO: B.C.’s seventh coronavirus patient at home in Fraser Health region

Canada in ‘containment’ as COVID-19 spreads in other countries

B.C. takes over another Retirement Concepts senior care home

Summerland facility latest to have administrator appointed

RCMP pull office from Wet’suwet’en territory, but hereditary chiefs still want patrols to end

Chief says temporary closure of field office not enough as Coastal GasLink pipeline dispute drags on

Prescription opioids getting B.C. addicts off ‘poisoned’ street drugs

Minister Judy Darcy says Abbotsford pilot project working

Royals, Elvis, Captain Cook: Hundreds of wax figures find new life in B.C. man’s home

Former director of Victoria’s Royal London Wax Museum still hopes to revive wax figure tourism

Teck CEO says Frontier withdrawal a result of tensions over climate, reconciliation

Don Lindsay speaks at mining conference, a day after announcing suspension of oilsands project

Okanagan man swims across Columbia River to evade Trail police

RCMP Cpl. Devon Reid says the incident began the evening of Thursday, Feb. 20

‘Hilariously bad’: RCMP looking for couple with forged, paper Alberta licence plate

Mounties said the car crashed when it lost a wheel but the duo ran away as police arrived

Most Read