Stratigraphic, sedimentologic, and dendrogeomorphic analyses of rapid floodplain formation along the Rio Grande in Big Bend National Park, Texas

Research Article| September 01, 2011 Stratigraphic, sedimentologic, and dendrogeomorphic analyses of rapid floodplain formation along the Rio Grande in Big Bend National Park, Texas D.J. Dean; D.J. Dean † 1Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, Utah 84322-5210, USA †E-mail: david.dean@usu.edu Search for other works by this author on: GSW Google Scholar M.L. Scott; M.L. Scott 2U.S. Geological Survey, Fort Collins Science Center, 2150 Center Avenue, Building C, Fort Collins, Colorado 80526-8118, USA Search for other works by this author on: GSW Google Scholar P.B. Shafroth; P.B. Shafroth 2U.S. Geological Survey, Fort Collins Science Center, 2150 Center Avenue, Building C, Fort Collins, Colorado 80526-8118, USA Search for other works by this author on: GSW Google Scholar J.C. Schmidt J.C. Schmidt 1Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, Utah 84322-5210, USA Search for other works by this author on: GSW Google Scholar Author and Article Information D.J. Dean † 1Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, Utah 84322-5210, USA M.L. Scott 2U.S. Geological Survey, Fort Collins Science Center, 2150 Center Avenue, Building C, Fort Collins, Colorado 80526-8118, USA P.B. Shafroth 2U.S. Geological Survey, Fort Collins Science Center, 2150 Center Avenue, Building C, Fort Collins, Colorado 80526-8118, USA J.C. Schmidt 1Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, Utah 84322-5210, USA †E-mail: david.dean@usu.edu Publisher: Geological Society of America Received: 30 Jul 2010 Revision Received: 06 Jan 2011 Accepted: 27 Jan 2011 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2011 Geological Society of America GSA Bulletin (2011) 123 (9-10): 1908–1925. https://doi.org/10.1130/B30379.1 Article history Received: 30 Jul 2010 Revision Received: 06 Jan 2011 Accepted: 27 Jan 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 D.J. Dean, M.L. Scott, P.B. Shafroth, J.C. Schmidt; Stratigraphic, sedimentologic, and dendrogeomorphic analyses of rapid floodplain formation along the Rio Grande in Big Bend National Park, Texas. GSA Bulletin 2011;; 123 (9-10): 1908–1925. doi: https://doi.org/10.1130/B30379.1 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 channel of the lower Rio Grande in the Big Bend region rapidly narrows during years of low mean and peak flow. We conducted stratigraphic, sedimentologic, and dendrogeomorphic analyses within two long floodplain trenches to precisely reconstruct the timing and processes of recent floodplain formation. We show that the channel of the Rio Grande narrowed through the oblique and vertical accretion of inset floodplains following channel-widening floods in 1978 and 1990–1991. Vertical accretion occurred at high rates, ranging from 16 to 35 cm/yr.Dendrogeomorphic analyses show that the onset of channel narrowing occurred during low-flow years when channel bars obliquely and vertically accreted fine sediment. This initial stage of accretion occurred by both bed-load and suspended-load deposition within the active channel. Vegetation became established on top of these fine-grained deposits during years of low peak flow and stabilized these developing surfaces. Subsequent deposition by moderate floods (between 1.5 and 7 yr recurrence intervals) caused additional accretion at rapid rates. Suspended-sediment deposition was dominant in the upper deposits, resulting in the formation of natural levees at the channel margins and the deposition of horizontally bedded, fining-upward deposits in the floodplain trough. Overall, channel narrowing and floodplain formation occurred through an evolution from active-channel to floodplain depositional processes. High-resolution dendrogeomorphic analyses provide the ability to specifically correlate the flow record to the onset of narrowing, the establishment of riparian vegetation, the formation of natural levees, and ultimately, the conversion of portions of the active channel to floodplains. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.