Do you know BC wildfires and floods are linked to each other?
British Columbia wildfires 2021 was the third-worst in its history. The towns which were on evacuation alert during summer wildfires were at flood risk in fall and winter. The flood that followed the wildfires was ‘the straw that broke the camel’s back’. The mystery behind these occurrences couldn’t remain forever unfathomed.
The recent studies of the satellite images suggested that the events are linked to each other. In the province of British Columbia wildfires starting in April and calming down at the end of September, led to the foundation for the deadly floods of November 2021.
Collapsed bridge along Coquihalla Highway at Juliet Creek.
When scientists mapped out the hot spots of previously burned-down woodland areas, they matched them with hotspots of the worst-hit flood zone. The result was astonishing.
The burned-scarred valleys from the July Mountain fire that destroyed both sides of the road are close to the Coquihalla Highway. These hills and slopes directly poured rainwater onto the major roadway creating havoc.
Water Resistant Forest?
An aerial shot of flooding on the Sumas Prairie in Abbotsford. Photograph: City of Abbotsford/AFP/Getty Images
No kidding! Haven’t heard of it before? Neither did I. Wildfires leading the foundation for the future floods have been known before worldwide. To make matters worse, when a wildfire burns, a tree’s leaves, and needles release aromatic oils that drip into the soil. “Once cool, they create an oily coating below the ash and soil, like wax paper” (UBC’s forestry department). This oil coating which is formed below the ashes on the top of the soil turns it into a water-resistant surface.
Hence, the forest which was highly absorbent and taking rainwater in is now failing to stay on that track. As a result of this effect, water accumulation turns into puddling and ultimately starts rushing down towards low-lying areas which are often occupied by human habitat and infrastructure. Flooded rivers guide a high volume of water to rush anywhere and everywhere into nearby towns, over the roads, bridges, and highways.
Clear cut Logging is another factor
An aerial shot of massive clear-cuts on Vancouver Islands.
British Columbia’s 2.6 million hectares of old-growth forest are at risk today. Some of the intact old-growth forests of Vancouver Island have been shaved off. This forest is said to be holding vast carbon storage as compared to the newly replanted trees. (In fact, the clear-cutting of B.C.’s forests is contributing more to greenhouse gases than the burning of fossil fuels, according to a new report from the Sierra Club of B.C. )
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Clear-cutting logging as shown in the map above is significant. This has increased the local temperature as well as created instability in the landscape in that area. Not only that, but studies also specify that around 50% of the lumber which is left behind to decompose or dry out in extreme heat, eventually act as a fuel for a forest fire.
Atmospheric River (AR)
The term atmospheric river first originated in 1998 by Massachusetts Institute of Technology researchers Yong Zhu and Richard Newell. It is a large narrow stream of water vapor that travels through the sky from oceans to land and particularly to mountainous regions like that of the British Columbia coast. These streams of water can sometimes dump in a month worth of rain in just a few days or merely a few hours. Unfortunately, AR is tied to climate change too. The intensity of AR has become powerful over time, and it lasts longer than it used to be in the past. It is estimated that if an atmospheric river’s storms could prompt up to 20 landslides over the North Shore Mountains overlooking North Vancouver, a stronger AR by the end of the century could cause 80 landslides.
Aggregating the increased threat from severe wildfires will add more ash to the hillsides in the future. This in turn can lead to more fluid landslides (Environment and Climate Change Canada (ECCC).
The immediate measure is preparing for these events ahead of time. Environment and Climate Change Canada (ECCC) is trying to create a new warning system with a Canadian version of scales to pin down and foresee the intensity of ARs and alert people before it comes down. The system would also include the probability of destruction that the AR is expected to cause such as mudslides, bank erosion, and bridge closure. An efficient system in place would give us extra time to bring floods under control.
Labbe, S. April 28th, 2022. Prince George Citizen, Local News. “Satellite mapping finds a correlation between B.C. wildfires and floods”. Retrieved from: https://www.princegeorgecitizen.com/local-news/satellite-mapping-finds-correlation-between-bc-wildfires-and-floods-5301312
Global Forest Watch, British Columbia, Canada. Forest Monitoring designed for Action. Retrieved from:” www.GlobalForestwatch.org”
Colleta A, Parker C. November 15th, 2021. Washington Post. ”Floods caused by an ‘atmospheric river’ trap people on highways, prompt evacuations in British Columbia. “ Retrieved from: https://www.washingtonpost.com/world/2021/11/15/canada-floods-british-columbia/
Kulkarni, A. Oct 4th, 2021. “CBC News, A look back at the 2021 B.C. wildfire season.” Retrieved from: https://www.cbc.ca/news/canada/british-columbia/bc-wildfires-2021-timeline-1.6197751