Vancouver residents and the rest of the Pacific Northwest watched in horror last summer when the Eagle Creek Fire ripped through the Columbia River Gorge.
When the fire was extinguished and the damage to some of the region’s most beloved hiking trails became apparent, the collective feelings of local recreationalists turned to a mix of outrage and impatience.
But in what he describes as “the most unscientific sciencey talk you’ll ever hear,” Steven Sobieszczyk, a hydrologist with the U.S. Geological Survey and science communicator, urged his audience to take a more contextual approach during Wednesday’s Science on Tap event at Kiggins Theatre.
Sobieszczyk unpacked the changes that fire brings to the landscape during a burn and long after it’s extinguished. Essentially, the landscape will recover over time, but the healing process will pose dangers to the public.
Sobieszczyk is a hydrologist primarily focused on watersheds and landslides but, as a trainee, he joined the members of a U.S. Forest Service Burned Area Emergency Response team that investigated and assessed the extent of the destruction.
“It was my first fire,” he said in an interview with The Columbian. “Everything had just been burned. Nature completely annihilated everything. … It was awe-inspiring.”
“The media coverage made it seem like an apocalypse … that would destroy our way of life,” Sobieszczyk said. But he added that in comparison to other fires that burned across the West last year, it was relatively small.
The Thomas Fire that burned through Southern California in late 2017 and earlier this year, for example, was much larger, he told the audience. That fire engulfed about 282,000 acres, destroyed or damaged about 1,300 homes, and killed more than 20 people due to mudflows. In some places, fires in Southern California burned hot enough to turn the soil’s clay into ceramiclike material. The soils in the Gorge didn’t have that problem, but the landscape poses its own risks.
The Gorge fire has increased the risk for flash floods and debris flows over the next several years.
Vegetation that would otherwise soak up material was burned away, and a waxy material was deposited into the soil, making it hydrophobic. Because the water won’t absorb well, it will run off and increase the risk for flash flooding during big storms.
However, Sobieszczyk said he expects that risk to last for only a couple of years.
As burned trees fall over, they will disturb the ground around them and crash into other trees, potentially causing debris flows over the next five to eight years.
Another scenario, though much more difficult to predict, Sobieszczyk said, are flash floods and debris flows created when trees fall into upper watersheds, dam them and eventually give way.
The Gorge is naturally a debris flow-prone area, but the elevated risks of those events aren’t uniform across the landscape, he said.
Sobieszczyk urged people to heed trail closures when they see them.
“Closures are there for good reason, because the Forest Service wants to keep people safe,” he said. “Just because we’re past the first winter doesn’t mean we’re safe.”
He also urged the audience to have empathy for the 15-year-old Vancouver boy who started the Gorge fire. The teen was ordered in May to pay nearly $37 million in restitution.
Sobieszczyk told stories of his own foolish teenage behaviors while pointing out that he was still a good student and Boy Scout, and went on to have a good career.
“Teenagers have and will always have an undeniable sense of immortality,” he said.