4 Investigates: Scientists work to understand post-wildfire mudslides

23 February 2023

USA – ALBUQUERQUE, N.M. – It is a cruel turn that the rain that helped stop the Calf Canyon/Hermit’s Peak Fire created the mud and floods that will turn it into a years-long torment.

Videos hastily shot on cellphones by the people who live in Mora, Buena Vista, Rociada, Las Vegas and elsewhere in the fire’s sooty shadow often feature a thought or two offered to no one in particular: “Starting to hit the road,” muttered an amateur videographer capturing Beaver Creek as its black, ash-filled waters overflowed its banks during last summer’s monsoon.

What the fire didn’t get, the flood destroyed.

State Sen. Pete Campos is in his fourth decade representing the towns along the eastern slope of the Sangre De Cristo Mountains. He’s seen the videos and heard discouragement creep into the voices of people who normally pride themselves on being determined.

“Yes, people are resilient, but they sure have mental scars that they’re going to carry for the rest of their lives,” he told 4 Investigates in his state Capitol office.

Just last week, Campos convinced his fellow lawmakers to front $100 million for badly needed disaster aid. Gov. Michelle Lujan Grisham signed the bipartisan funding bill on Monday.

Within weeks, the snow that blankets the mountains will begin to melt and people who live in his district will once again worry the hills will flow down on top of them.

Watching and wondering

Five years ago, Ingrid Tomac watched the TV news from her San Diego home. Deadly mudslides had raced down the hills east of Montecito and Santa Barbara, California. What was then one of the state’s largest wildfires had charred the coastal mountain range a few months earlier. The mud overwhelmed drainage systems, bridges, ditches and retaining walls — killing more than a dozen people who never saw it coming.

An assistant professor at the School of Structural Engineering at the University of California San Diego, Tomac wondered why post-wildfire mudslides tended to be so much more destructive.

“They carry heavy boulders down the hill. Those boulders are shaking houses, breaking windows and breaking walls,” she said. “And I think we think it’s because it’s at least partially related to the air that we think it’s intermixed inside, which is a completely novel idea.”

Tomac theorizes wildfires trap a layer of air below burned soil. When it rains, she thinks scorched soil particles are attracted air bubbles instead of water. Scientists call soil like this “hydrophobic.”

“If this is going down the hill, it’s completely different,” she said.

On a large scale, she thinks that difference helps make post-wildfire mudslides so destructive.

“Then I think that we don’t have very good model of how everything flows down the hill and how it impacts infrastructure,” she explained.

She began testing how hydrophobic soil interacted with stirred up water first in her kitchen blender, then in a lab at UCSD, then she came up with the idea to test the interaction in space, where gravity wouldn’t be in the mix.

Last November, a rocket launched from Virginia with her experiment inside. After the Cygnus module docked with the International Space Station, astronauts aboard the ISS powered up the experiment and for a few weeks, Tomac and her team gathered data.

There’s still work to be done analyzing the results, but Tomac believes her science can help predict the forces that homes, bridges and dams might need to withstand if they’re in the path of post-wildfire mud flows.

Trusting science, waiting for federal money

“It is very important to actually look at what is the latest science,” said Congresswoman Teresa Leger Fernandez.

Along with others in New Mexico’s Congressional Delegation, the Las Vegas native helped secure billions of dollars in federal assistance for the fire complex that grew out of two U.S. Forest Service controlled burns.

Leger Fernandez sees promise in the science “it’s an avalanche of mud and soil and androcks and trees.”

But she said the people she knows who live in the path first of fire and now of mudslides are eager to get help rebuilding and getting back to the land that’s been part of their lives for generations.

23. February 2023/by GFMCadmin