The evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances: A wildfire and a historic flood

Details

• Journal Title:
  Geomorphology
• Personal Author:
  Rengers, F.K. ; McGuire, L.A. ; Ebel, B.A. ; Tucker, G.E.
• NOAA Program & Office:
  CIRES (Cooperative Institute for Research in Environmental Sciences)
• Description:
  The transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape-scale disturbances. The first disturbance, a high-severity wildfire, changed the catchment hydrology to favor overland flow, which incised a colluvial hollow, creating a channel in the same location. This incised channel became armored with cobbles and boulders following repeated post-wildfire overland flow events. Three years after the fire, a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps. An analysis of the step spacing shows that after the flood, newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow (prior to channelization). This suggests that despite a distinct change in channel form roughness and bedform morphology, the endogenous roughness periodicity was conserved. Variations in sediment erodibility helped to create the emergent steps as the largest particles ( >D84) remained immobile, becoming step features, and downstream soil was easily winnowed away.
• Source:
  Geomorphology, 309, 121-130
• DOI:
  https://doi.org/10.1016/j.geomorph.2018.01.003
• ISSN:
  0169-555X
• Format:
  pdf
• Publisher:
  Elsevier BV
• Document Type:
  Journal Article-Accepted Manuscript
• Rights Information:
  Accepted Manuscript
• Rights Statement:
  The NOAA IR provides access to this content under the authority of the government's retained license to distribute publications and data resulting from federal funding. While users may legally access this content, the copyright owners retain rights that govern the reproduction, redistribution, and re-use of this work. The user is solely responsible for complying with applicable copyright law.
• Compliance:
  Library
• Main Document Checksum:
  urn:sha-512:8e9b98feb4de60ac2cbefd29b18dd1d9714fc181c0a705f7676534f6770f5a591f9ba262c78e166f8284def86b413f23f1c3f3a121c336b1b7a4d8dba076d5e3
• Download URL:
  https://repository.library.noaa.gov/view/noaa/68320/noaa_68320_DS1.pdf
• File Type:
  [PDF - 15.62 MB ]