For survivors of California wildfires, next danger could come from water, UB expert says

BUFFALO, N.Y. — As deadly wildfires rage in California, the next big risk to areas that have been burned could come from water, says Chris Renschler, a University at Buffalo expert in integrated watershed management and disaster response.

“Trees and other vegetation have burned away, and where the fire was intense, soils can become hydrophobic. This means the soil absorbs much less water than before, if any, and it can lead to increased surface runoff, creating a higher risk of flash floods and landslides that can endanger both people and property,” Renschler says. “It’s something that residents and downstream neighbors of burned areas need to be aware of, because even after the fire is extinguished, you can face problems with increased runoff during rain storms.”

“One of the biggest problems now is that these fires are happening with a frequency and a scale that we haven’t seen before,” he says. “The sheer size of these burned areas changes the conditions of the landscape in terms of its land cover and rainfall-runoff behavior.”

Renschler, PhD, is an associate professor of geography in UB’s College of Arts and Sciences and director of the Landscape-based Environmental System Analysis and Modeling (LESAM) lab at UB.

Flooding, soil erosion and integrated watershed management are important areas of focus for his research team that led to the development of watershed modeling techniques that have been used in Burned Area Emergency Response for emergency risk management assessment in post-wildfire situations over the past 15 years.

Renschler notes that in early 2018, mud flows in Southern California took many lives and injured numerous people downstream from areas devastated by wildfires. This summer, he traveled to one of the hardest hit communities — the Montecito area — to gain an understanding of the scope of the destruction by viewing debris flows with a fire captain who was involved in disaster response.

And landslides are only one of the likely problems that storms can create for communities working to recover from wildfires, Renschler says.

“Think of all the stuff that people have in their homes and garages that burned up and that’s just lying around now,” Renschler says. “Even with less extreme runoff after a storm, ash with all kinds of contaminants — all these toxins — are being rushed down into streams and rivers. From an ecological perspective, streams will be impacted.”