Fire effects on geomorphic processes

Post‐Fire Sediment Yield From a Central California Watershed: Field Measurements and Validation of the WEPP Model

“…Our field-estimated post-fire sediment yield having been 3.5 to 4.6 times greater than the long-term rate represents a relatively small increase compared to most other situations reported in the literature. Post-fire sediment yields can be anywhere from 1.2 to 1,600 times above pre-fire values; one to two orders of magnitude increase is common (McGuire et al, 2024;Owens et al, 2013;Shakesby & Doerr, 2006), as observed also in one northern California study (East et al, 2021). However, some of the higher values in literature examples included situations with post-fire debris flows, not directly comparable with the watershed above Los Padres Dam in 2016-2017.…”

“…Understanding these responses is particularly important in our region of interest because California is anticipated to experience 18% greater rain intensity by the late 21st century (Flint & Flint, 2012;Prein et al, 2017), more severe drought (Swain et al, 2018), and larger, more severe fires (Goss et al, 2020;Rogers et al, 2020), all contributing to increasing sediment export (East & Sankey, 2020;McGuire et al, 2024;Sankey et al, 2017). Similar increases in fire and post-fire erosion are anticipated in some other regions beyond the western U.S. as well, particularly the Mediterranean area (McGuire et al, 2024;Morán-Ordóñez et al, 2020). Our findings from the Carmel River watershed provide quantitative information from a cascade of hydroclimatic extremes: the historic 2012-2015 drought (i.e., reduced plant moisture made fuels more easily combustible and weakened or killed trees that stabilize slopes), the 2016 Soberanes Fire, and the 2017 extreme wet season.…”

“…The sediment export from such landscapes after fire and flooding can be hazardous to downstream communities, reduces the useful life of reservoirs, or can change coastal morphology, sometimes for years or decades (Warrick et al, 2022(Warrick et al, , 2023. Understanding these responses is particularly important in our region of interest because California is anticipated to experience 18% greater rain intensity by the late 21st century (Flint & Flint, 2012;Prein et al, 2017), more severe drought (Swain et al, 2018), and larger, more severe fires (Goss et al, 2020;Rogers et al, 2020), all contributing to increasing sediment export (East & Sankey, 2020;McGuire et al, 2024;Sankey et al, 2017). Similar increases in fire and post-fire erosion are anticipated in some other regions beyond the western U.S. as well, particularly the Mediterranean area (McGuire et al, 2024;Morán-Ordóñez et al, 2020).…”