Post-Fire Sediment Research at the Pacific Coastal and Marine Science Center

The USGS Pacific Coastal and Marine Science Center (PCMSC) has been growing our post-fire research contributions since 2017, through studies of post-fire sediment movement that address the Natural Hazards Mission Area objectives for understanding wildfire hazards. PCMSC scientists collaborate with the USGS Landslide Hazards Program, California Geological Survey, National Park Service, and academic researchers to record landscape responses including debris flows and the rain conditions associated with them, focusing on northern California where data are relatively sparse. 

PCMSC has also led a series of case studies measuring post-fire sediment delivery to reservoirs. These investigations, including work funded by Supplemental disaster appropriations after the 2018 Carr Fire and 2021 Caldor Fire, utilize the sediment-trapping depositional environment of reservoirs to measure sediment yields from burned watersheds. By surveying a reservoir repeatedly over several years after a fire, we can use measured changes in sediment volume to calculate how much sediment has eroded from burned terrain upstream. The resulting data not only provide valuable information to water-resource managers on risk to water supply (some reservoirs lose substantial storage space due to post-fire sediment delivery), but also generate important field-based data that we then use to validate post-fire erosion models, improving prediction capabilities for future post-fire situations. 

Our scientists also trace the effects of fire and subsequent extreme rainfall to evaluate coastal responses to increased sediment supply, and evaluate geochemical effects of fires in rural and more urbanized landscapes, tracing chemical contaminants. PCMSC is now working up results from several field studies of recent fires in California and Hawaii, and preparing to publish a slew of modeling results led by our Mendenhall post-doctoral fellow Dr. Helen Dow on post-fire sediment mobilization across almost 200 large California fires since 1984.

Funding:

Funding for this project is provided by the Robert T. Stafford Disaster Relief and Emergency Assistance Act (42 U.S.C. 5121 et seq.) and supplemental funding acts for Federal disaster relief activities. Through this funding, USGS supports recovery efforts in declared natural disaster areas, to aid recovery efforts from widespread wildfires, devastating hurricanes, prolonged volcanic eruptions, and damaging earthquakes. This enables USGS to repair and replace equipment and facilities, collect high-resolution elevation data, and conduct scientific studies and assessments to support recovery and rebuilding decisions.