Arroyo channel head evolution in a flash-flood–dominated discontinuous ephemeral stream system

Research Article| November 01, 2014 Arroyo channel head evolution in a flash-flood–dominated discontinuous ephemeral stream system Stephen B. DeLong; Stephen B. DeLong † 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA †E-mail: sdelong@usgs.gov. Search for other works by this author on: GSW Google Scholar Joel P.L. Johnson; Joel P.L. Johnson 2Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Kelin X Whipple Kelin X Whipple 3School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85281, USA, and Canadian Institute for Advanced Research, 180 Dundas W, Toronto, Ontario M5G 1Z8, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Stephen B. DeLong † 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA Joel P.L. Johnson 2Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Kelin X Whipple 3School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85281, USA, and Canadian Institute for Advanced Research, 180 Dundas W, Toronto, Ontario M5G 1Z8, Canada †E-mail: sdelong@usgs.gov. Publisher: Geological Society of America Received: 10 Jan 2014 Revision Received: 12 May 2014 Accepted: 02 Jun 2014 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2014 Geological Society of America GSA Bulletin (2014) 126 (11-12): 1683–1701. https://doi.org/10.1130/B31064.1 Article history Received: 10 Jan 2014 Revision Received: 12 May 2014 Accepted: 02 Jun 2014 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Stephen B. DeLong, Joel P.L. Johnson, Kelin X Whipple; Arroyo channel head evolution in a flash-flood–dominated discontinuous ephemeral stream system. GSA Bulletin 2014;; 126 (11-12): 1683–1701. doi: https://doi.org/10.1130/B31064.1 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 We study whether arroyo channel head retreat in dryland discontinuous ephemeral streams is driven by surface runoff, seepage erosion, mass wasting, or some combination of these hydrogeomorphic processes. We monitored precipitation, overland flow, soil moisture, and headcut migration over several seasonal cycles at two adjacent rangeland channel heads in southern Arizona. Erosion occurred by headward retreat of vertical to overhanging faces, driven dominantly by surface runoff. No evidence exists for erosion caused by shallow-groundwater–related processes, even though similar theater-headed morphologies are sometimes attributed to seepage erosion by emerging groundwater. At our field site, vertical variation in soil shear strength influenced the persistence of the characteristic theater-head form. The dominant processes of erosion included removal of grains and soil aggregates during even very shallow (1–3 cm) overland flow events by runoff on vertical to overhanging channel headwalls, plunge-pool erosion during higher-discharge runoff events, immediate postrunoff wet mass wasting, and minor intra-event dry mass wasting on soil tension fractures developing subparallel to the headwall. Multiple stepwise linear regression indicates that the migration rate is most strongly correlated with flow duration and total precipitation and is poorly correlated with peak flow depth or time-integrated flow depth. The studied channel heads migrated upslope with a self-similar morphologic form under a wide range of hydrological conditions, and the most powerful flash floods were not always responsible for the largest changes in landscape form in this environment. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.