Plant Moisture Levels Help Predict Wildfires

SCE launches its first vegetation sampling program as part of its ongoing wildfire mitigation efforts.
Photo Credit: Elisa Ferrari and LACoFD

As Matthew Malle and his team search for new growth on branches and other vegetation in the hills above Santa Clarita in Los Angeles County, he knows how critical this process is when figuring out the wildfire risk in the area.

“Live fuel moisture sampling is the main factor in determining how brush will burn during a wildfire,” said Malle, a biologist. “The more moisture plants have, the less chance they will burn.”

The data collected through this process will improve the accuracy of Southern California Edison’s live fuel moisture computer modeling, which will eventually be used to predict wildfires in high fire risk areas. The data is already being shared with fire agencies and the public through the National Fuel Moisture Database

Tom Rolinski, SCE fire scientist, looks for vegetation to collect to test the moisture level.
Tom Rolinski, SCE fire scientist, looks for vegetation to collect to test the moisture level.

Malle works for AECOM, a company that recently helped with a live fuel moisture sampling pilot program with SCE and the L.A. County Fire Department. The data collected was one of the determining factors in launching SCE’s live fuel moisture sampling program, part of the company’s 2019 Wildfire Mitigation Plan.

“The pilot program ran from June to August and was highly effective,” said Tom Rolinski, SCE’s fire scientist who oversees the utility’s new live fuel moisture sampling program. “We’ve always relied on live fuel moisture sampling data from fire agencies, but there are gaps in some of the data.”

About a quarter of SCE’s service area is vulnerable to potential wildfires. Some high fire risk locations where vegetation will be collected include: Idyllwild, Banning Pass, Hemet and L.A. County along the 14 Freeway. Malle collects up to 50 grams of vegetation each day. As soon as each plant is clipped, it’s placed in a container and sealed since it starts losing moisture immediately.

As we continue to fill those data gaps, the information will also help refine SCE’s decision-making process when it comes to potentially turning the power off during extreme weather conditions. That’s something the utility takes very seriously and never wants to do unless it’s absolutely necessary.”

Tom Rolinski, SCE Fire Scientist

“SCE’s fuel moisture program is based on a program that was created by the U.S. Forest Service and is also used by fire agencies like the L.A. County Fire Department,” Malle said. “We do not collect samples when the chaparral foliage is wet from rain, dew or fog. Errors can occur if plants are collected during wet months and we want the most accurate data possible.”

The vegetation is then taken back to a lab to undergo moisture level testing. All the plant samples remain in a container and are weighed to determine the moisture amount. The process also involves placing plant samples in an oven at about 200 degrees for up to 20 hours. 

“As we continue to fill those data gaps, the information will also help refine SCE’s decision-making process when it comes to potentially turning the power off during extreme weather conditions,” Rolinski said. “That’s something the utility takes very seriously and never wants to do unless it’s absolutely necessary.”