Want to mitigate overland flood risk? Check upstream as well as downstream

B.C. documentary filmmaker Daniel Pierce has focused his lens on how deforestation, combined with climate change, elevates the risk of flood damage in the province’s river basins.

Pierce appeared by video link at the CatIQ Connect claims conference in Toronto last Tuesday. He spoke about his 25-minute documentary, Trouble in the Headwaters, which premiered in Victoria, B.C., in June 2025.

Presented by The Narwhal, the film analyzes root causes behind the 2018 floods in Grand Forks, B.C., where more than 100 families were displaced and an estimated $38 million in damage was caused to more than 500 buildings in the flooded area.

Much of the damage was not eligible for insurance coverage, since policy deductibles for overland flood ranged between $2,000 and $100,000, brokers reported to Canadian Underwriter at the time.

Pierce’s film features Dr. Younes Alila, a professor of forest hydrology at the University of British Columbia. Alila published a controversial academic research paper in 2009 claiming, in very basic terms: “While large floods may not appear to increase much in magnitude [due to loss of tree cover], they may occur more frequently as a result of forest harvesting or deforestation.”

Pierce’s film features Alila and specifically analyzes the impact of clear-cut logging on flooding in the Kettle River watershed in the Grand Forks area.

“When the 2018 flood happened…reports started to arise that this wasn’t just a climate event; it wasn’t just about the rain and the snow,” Pierce told property and casualty insurance professionals via video link to the conference. “There was actually more going on in the landscape upstream from Grand Forks, in the broader Kettle River basin.

“A lot of people were saying that this was connected to clearcut logging all throughout the headwaters of the Kettle, and so I decided to shift my focus as a journalist and go check this out and talk to people on the ground.”

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Pierce cited images in his film of a 600-hectare logging clearcut in the area, which he said was supposed to be limited by regulation to 40 hectares. Since the 1980s, he noted, time lapse photography by Google Maps showed a significant amount of deforestation happening in areas of the basin. This, Alila claims in his research, increases the frequency of extreme flooding events attributed to climate change.

“What Dr. Alila’s research has really revealed is that…when all the other climate factors remain the same, that forest cover does a ton of work in lowering the risk and lowering the amount of runoff that comes down into stream channels,” Pierce told CatIQ delegates. “And when you remove that forest cover…that [natural] mechanism [or reducing flood risk] is lost, and the water comes pouring off the hillsides all at once.”

Depending on the nature of the watershed, clearcut logging can increase the frequency of floods by anywhere between five and 18 times the pre-disturbed forest cover, Pierce said.

“That means structures we designed to withstand a 100-year flood are now in a lot of danger, and are no longer going to be sufficient in the long run, because that 100-year flood could now become a 10-year flood or a five-year flood.”

Pierce cited the example of Abbotsford, B.C., a city of more than 150,000 people in the province’s Fraser Valley. Severe flooding from an atmospheric river in 2021 caused more than $670 million in insured damage in the area, as Insurance Bureau of Canada reported last year.

Abbotsford flooded again in 2024, and yet again in December 2025. The 2025 flooding, caused by an atmospheric river, resulted in estimated insured damage of $90 million.

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Pierce noted the 2021 floods in Grand Forks led to a “managed retreat,” including the city buying out 100 properties with a backing of $50 million. In Spring 2024, the province introduced a 10-year plan for flood risk mitigation in the area, but a Vancouver Sun report noted the plan had “no price tag, no project priorities, and no timelines.”

Pierce said insurers tend to deal with the natural disasters caused downstream. But, in addition to climate change, they should be considering how deforestation upstream can be contributing to the frequency of flood events.

“The most important thing is that, if we’re going to be making millions — if not billions — of dollars of investments in the downstream to mitigate flood risk, we must synchronize our policies in the upstream to make sure we’re not continuing to make the problem worse,” Pierce said. “[We should also be] doing restoration and careful stewardship and bringing back the intact forest covering the upstream, so that we can lower that risk over time.

“That is a generational project that needs to be committed to in the long haul.”

Editor’s Note: The article has been updated to reflect that the 2021 floods to which Pierce referred were in Grand Forks, B.C., now Abbotsford, as previously reported. CU apologizes for the error.

David Gambrill

David has twice served as Canadian Underwriter’s senior editor, both from 2005 to 2012, and again from 2017 to the present.