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Lake Oroville Debris Volume and Impact Survey

In 2023, significant floating debris accumulated in Lake Oroville due to above-average precipitation and recent wildfires. Wildfires have notably impacted water quality and sediment transport in reservoirs. To help plan for future maintenance needs, the California Department of Water Resources (DWR) wanted to conduct a comprehensive survey to estimate the debris volume. They reached out to our team for help.

We used debris flow, hydrologic and hydraulic, and sediment transport modeling to assess sediment transport from medium and small watersheds to Lake Oroville. To estimate the debris volume, we used aerial drone photogrammetry and volumetric measurements, a complex process due to irregular piles and void spaces within the debris. We then compared the 2023 debris volume to that of previous years and our modeling estimates, providing valuable data for managing debris in Lake Oroville.

While dams formed by post-wildfire large debris can reduce downstream impacts, transport of large debris poses a threat to infrastructure and water quality. This study highlighted the need to understand debris transport dynamics to manage debris more effectively once it arrives at reservoirs.

DWR compared model results to the amount of large woody debris removed in 2022¨C2023. They found that the volume of debris they removed was within the range we had estimated, providing validation of the modeling techniques used.