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Increased Sediment Loadings into Coastal Waters Following Wildfire: A Remote Sensing and Modeling Perspective
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  • Amanda Mulcan Lopez,
  • Tesfa Meshesha,
  • Christine Lee,
  • Ibrahim Nourein Mohammed,
  • Erin Hestir,
  • Thomas Harmon,
  • Dulcinea Avouris
Amanda Mulcan Lopez
NASA Jet Propulsion Laboratory

Corresponding Author:[email protected]

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Tesfa Meshesha
University of California, Merced
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Christine Lee
NASA Jet Propulsion Laboratory
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Ibrahim Nourein Mohammed
NASA Goddard Space Flight Center
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Erin Hestir
https://www.ucmerced.edu/
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Thomas Harmon
University of California, Merced
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Dulcinea Avouris
USGS California Water Science Center
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Abstract

Coastal watersheds impacted by wildfires experience increased sediment delivery to the ocean that alter the availability of limiting factors (i.e., light) for marine organisms. With increasing wildfire magnitude and severity, it is critical to explore changes in riverine discharges to the ocean to assess cascading hazards associated with wildfires. In situ data and a hydrological model adapted to capture fire-related land use change are paired with remotely sensed turbidity data to investigate Woolsey Fire impacts on Malibu Creek, California, USA. Maximum post-fire observed and simulated discharges and sediment loads were between 1.4 – 4.8 and 0.93 – 13.9 times higher, respectively, than during non-fire periods with similar rainfall. Mean turbidity also increased to 18.2 Formazin Nephelometric Unit (FNU) during the first storm post-fire (mean background value of 4.3 FNU). Synergies between the methods were able to better characterize post-fire sediment fluxes versus a single method. Notably, remote sensing observations captured rapid coastal sediment exports within the first post-fire month that SWAT did not. Conversely, sporadic remote sensing observations did not reflect ongoing post-fire sediment erosion (largely due to cloud cover issues), which SWAT did demonstrate. These data are essential to understanding fire-related marine ecological changes and implementing effective management and conservation initiatives.
10 Jul 2024Submitted to ESS Open Archive
11 Jul 2024Published in ESS Open Archive