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.

 

Just Posted

VIDEO: Explorers uncover Canada’s deepest cave in Fernie

The cave, named Bisaro Anima, was confirmed to have broken the record on New Year’s Day

New Glade ferry enters testing phase

The Glade II will be able to carry heavier loads and will use less greenhouse gases.

Freezing rain warning in effect for B.C. Southern Interior

Environment Canada issued the freezing rain warning for most of the Southern Interior Tuesday morning

Rumble In The Rockies brings live boxing back to Fernie

Local boxer, Dylan Mitchell takes first career win at home

Smiles all around as province announces emergency ward funding

$2.1 million to go to much-needed upgrades

VIDEO: Orcas put on a show near Hornby Island

Louis Jobodin shares photos and video of his experience

Body discovered in burnt out car near Trail

Police report a body was found in the burnt out trunk of a 1999 Honda Civic

VIDEO: B.C. Lions sign defensive back T.J. Lee to contract for upcoming season

The four-year veteran had a team-high four interceptions and 49 tackles last season with B.C.

How an immigrant to Canada helped Donald Trump prove his mental health

Test that cleared Trump was developed by doctor associated with McGill and Sherbrooke universities

Premier touches on multiple topics ahead of Asia trade trip

Housing and childcare are expected to be the focus of the BC NDP’s first budget in February.

UPDATE: Friends mourn boy, 15, killed in Vancouver shooting

John Horgan: ‘No stone is to be left unturned until we find the perpetrator of this heinous crime’

Vernon to host largest Special Olympics B.C. Winter Games in 2019

Games to be held Feb. 21-23, with more than 800 athletes expected to take part

Ex-BC Liberal staffer focused on ‘favourable’ ethnic communities in scandal: lawyer

Former communications director Brian Bonney’s sentencing hearing for breach of trust is underway

Sunwing vacation passengers left at Abbotsford airport

YXX staffers receive praise for help to passengers; airline criticized

Most Read