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October 21, 2021 – The Cosumnes River watershed is representative of many in California in that it extends from the Sierra Nevada mountain range to the Central Valley, providing water and recharging aquifers for municipal and agricultural regions, but unique in that it’s one of the last major rivers without a large-scale dam, enabling the study of natural rivers flows. In 2017 Lawrence Berkeley National Laboratory scientist Erica Siirila-Woodburn, a hydrologist by training, decided it would be an excellent place to study how climate extremes affect mountain water cycles. Working with colleagues, she built an advanced hydrologic model to investigate how events such as drought and wildfire would affect things like groundwater levels and streamflow.

Fast forward four years, and the Caldor Fire erupted in the headwater forests of the Cosumnes River basin, growing to become the 16th largest fire in California state history. Berkeley Lab scientists mobilized quickly to collect data from the burned area. The data will then be rapidly incorporated within the developed model to predict how the ecosystem is likely to respond to precipitation events this winter.  

With escorts from the U.S. Forest Service, small teams of scientists traveled to burn areas in September and October to collect samples of water, sediment, and ash. The scientists are now analyzing those samples to quantify, for example, the concentration of all major ions, dissolved organic and inorganic carbon, various nitrogen species, and stable water isotopes. They are also collecting information to inform how soil properties change post-fire, including water repellency and erosion. 

Berkeley Lab scientist Jasquelyn Peña, UC Davis postdoc Kyounglim Kang, and U.S. Forest Service hydrologist Vince Pacific collect water samples from a creek in Capps Creek Crossing. Photo: Marilyn Sargent/Berkeley Lab

Sample collection will continue through the winter with assistance from more than 30 citizen scientists organized by a local conservancy group, the American River Conservancy. “These ‘storm chaser’ volunteers will enable us to rapidly measure water quality over a large region following precipitation events in this crucial time post-fire,” Siirila-Woodburn said.

The data collected will help address both short- and long-term needs. In the short term, the information will be used to predict if certain areas are more vulnerable to flooding, erosion, and debris flow. It could also shed light on water quality and potential exposure to toxic compounds. In the longer term, it will improve the model that has been built and help scientists better understand how mountain ecosystems respond to fires. 

The efforts are part of a larger initiative at Berkeley Lab to develop scientific approaches to understand, predict, and aid response to wildfires.

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams,Lawrence Berkeley National Laboratoryand its scientists have been recognized with 14 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visitenergy.gov/science.