The effects of wildfire on the sediment yield of a coastal California watershed

Abstract

Research Article| July 01, 2012 The effects of wildfire on the sediment yield of a coastal California watershed J.A. Warrick; J.A. Warrick † 1U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California 95060, USA †E-mail: jwarrick@usgs.gov Search for other works by this author on: GSW Google Scholar J.A. Hatten; J.A. Hatten 2College of Forest Resources, Mississippi State University, Mississippi State, Mississippi 39762, USA Search for other works by this author on: GSW Google Scholar G.B. Pasternack; G.B. Pasternack 3Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA Search for other works by this author on: GSW Google Scholar A.B. Gray; A.B. Gray 3Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA Search for other works by this author on: GSW Google Scholar M.A. Goni; M.A. Goni 4College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar R.A. Wheatcroft R.A. Wheatcroft 4College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2012) 124 (7-8): 1130–1146. https://doi.org/10.1130/B30451.1 Article history rev-recd: 29 Nov 2011 accepted: 08 Dec 2011 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation J.A. Warrick, J.A. Hatten, G.B. Pasternack, A.B. Gray, M.A. Goni, R.A. Wheatcroft; The effects of wildfire on the sediment yield of a coastal California watershed. GSA Bulletin 2012;; 124 (7-8): 1130–1146. doi: https://doi.org/10.1130/B30451.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The occurrence of two wildfires separated by 31 yr in the chaparral-dominated Arroyo Seco watershed (293 km2) of California provides a unique opportunity to evaluate the effects of wildfire on suspended-sediment yield. Here, we compile discharge and suspended-sediment sampling data from before and after the fires and show that the effects of the postfire responses differed markedly. The 1977 Marble Cone wildfire was followed by an exceptionally wet winter, which resulted in concentrations and fluxes of both fine and coarse suspended sediment that were ∼35 times greater than average (sediment yield during the 1978 water year was 11,000 t/km2/yr). We suggest that the combined 1977–1978 fire and flood had a recurrence interval of greater than 1000 yr. In contrast, the 2008 Basin Complex wildfire was followed by a drier than normal year, and although suspended-sediment fluxes and concentrations were significantly elevated compared to those expected for unburned conditions, the sediment yield during the 2009 water year was less than 1% of the post–Marble Cone wildfire yield. After the first postfire winters, sediment concentrations and yield decreased with time toward prefire relationships and continued to have significant rainfall dependence. We hypothesize that the differences in sediment yield were related to precipitation-enhanced hillslope erosion processes, such as rilling and mass movements. The millennial-scale effects of wildfire on sediment yield were explored further using Monte Carlo simulations, and these analyses suggest that infrequent wildfires followed by floods increase long-term suspended-sediment fluxes markedly. Thus, we suggest that the current approach of estimating sediment yield from sediment rating curves and discharge data—without including periodic perturbations from wildfires—may grossly underestimate actual sediment yields. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.