By Taylor Emerson ’18

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A wildfire is a dazzling spectacle of dread and destruction. 

As it dances through a landscape, it moves and bends with the wind, sometimes created from the depths of its own consumption. Its yellow-orange light has tantalized and traumatized generations of humans and animals alike — stretching back eons to Earth’s creation. 

The smoke and ash produced from the flames darkens and reddens the sun, sometimes for hundreds of miles, signaling that somewhere the world is alight.

Left in the wake of this brightness and heat is a place darkened and muted. And like its creator, it is itself now a manufacturer of mayhem.

Burn scars, as the name suggests, are the semi-permanent remains of a landscape torched by wildfires — charred trees, burned-over bushes, and soil that’s been baked by temperatures reaching thousands of degrees Fahrenheit.

As a result, “the soil becomes very hydrophobic,” says Belize Lane, a watershed hydrologist with the Utah Water Research Laboratory.

This means where once water would have been absorbed into the ground, it tends to rush and run off this new landscape — like asphalt. Instead of soaking into the soil or otherwise being slowed by the trees and vegetation vying for that nourishment, the water swells and picks up speed as it moves downslope, sweeping into it all the debris left behind by the fire.

“The soil essentially acts like its paved over,” Lane says. “Water is just going to run right over the surface.” 

When this water reaches a stream or river, or creates its own where there is none, it leads to intense flooding events — damaging homes, roads, and other critical infrastructure.

Utah is no stranger to this, as just this summer several megafires have burned within mere miles of cities and towns. Beaver, Fillmore, Kanosh, Meadow and Henefer have all seen flames tear through the mountains and hillsides above them and faced the resulting flooding risks.

“Oftentimes the effects of a wildfire can last for anywhere from one to up to six years after a fire,” Lane says.

To help mitigate these impacts, Lane, along with her cohort of researchers, is developing models to help predict and plan for downstream impacts to communities and ecosystems as a result of burn scars.

They do this by getting out, boots-on-the-ground, in recently extinguished burn scars — like the Cottonwood Fire, which they visited in August. The team takes measurements on soil infiltration, or how easily water is absorbed into the ground, to note how severe the wildfire has burned the area. They also compare the streamflow and sediment response to storms before and after the fire.

They take this real-world data and compile it into their models, with the aim of predicting how intense the flooding and sediment hazards could be in response to a range of plausible storm events. They are also developing approaches to predict post-fire hazards before a fire even occurs, given how rapidly fires and floods can ensue. 

“We know we’re facing this increasingly fire-prone future,” Lane says. “Can we come in with some projections of what burn severity could look like if a fire occurred… to help inform community and infrastructure design and planning based on where and how large we expect post-fire hazards to be.” 

These models can then be rapidly revised with observed burn severities after an event occurs to support emergency management and recovery.

“So even if we don’t know the actual answer, we can start to plan and design for this future we’re actively moving into,” Lane says.

Prevention planning could involve measures such as resizing stormwater culverts to account for larger runoff, designing or redesigning roadways away from potential mudslide or rockfall dangers, and accounting for sudden increases in sediment deposits in reservoirs or near dams.

But the models can also support rapid mitigation efforts post fire, by aiding communities, state and federal agencies in identifying the most at-risk areas. This means that these agencies and experts can then direct soil stabilization and debris clearing efforts toward high-priority sites first, working preemptively to prevent severe damage downslope and downstream.

“Our models can help with all of that,” says Lane, in regard to helping communities plan for or prevent burn scar-related issues.

Currently the researchers are working collaboratively with numerous state agencies across the western United States, training them how to use and implement the models into their own work. Through this process, they are also soliciting feedback from these users to help improve the models for future use.

“We’re hoping as we move forward [we can] continue to get more feedback and continue to improve our predictive capabilities in terms of post-fire flooding and debris flow and sedimentation risk — so that these tools can get better and better,” Lane explains.