The importance of erosion in distributary channel network growth, Wax Lake Delta, Louisiana, USA

Abstract

Research Article| January 01, 2014 The importance of erosion in distributary channel network growth, Wax Lake Delta, Louisiana, USA John B. Shaw; John B. Shaw Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA *Current address: Department of Geology and Geophysics, University of Wyoming, Department 3006, Laramie, Wyoming 82071, USA. Search for other works by this author on: GSW Google Scholar David Mohrig David Mohrig Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Author and Article Information John B. Shaw *Current address: Department of Geology and Geophysics, University of Wyoming, Department 3006, Laramie, Wyoming 82071, USA. Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA David Mohrig Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA Publisher: Geological Society of America Received: 20 May 2013 Revision Received: 11 Sep 2013 Accepted: 12 Sep 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2013 Geological Society of America Geology (2014) 42 (1): 31–34. https://doi.org/10.1130/G34751.1 Article history Received: 20 May 2013 Revision Received: 11 Sep 2013 Accepted: 12 Sep 2013 First Online: 09 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 John B. Shaw, David Mohrig; The importance of erosion in distributary channel network growth, Wax Lake Delta, Louisiana, USA. Geology 2014;; 42 (1): 31–34. doi: https://doi.org/10.1130/G34751.1 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 SocietyGeology Search Advanced Search Abstract A river delta’s shape and kinematics are dictated by the three-dimensional evolution of its distributary channels on the delta front, yet measurements of this evolution are scarce. We supply four bathymetric surveys documenting this evolution for Gadwall Pass—part of the Wax Lake Delta, one of the few rapidly prograding regions of the greater Mississippi Delta in coastal Louisiana, United States. This distributary channel extends 2–6 km beyond the sub-aerially emergent delta (dependent on water surface elevation) and bifurcates into four similarly sized distributary channels (average channel width = ∼150 m) in this sub-aqueous reach. Distributary channel growth proceeds primarily through erosion of the unchannelized foreset deposit, and growth patterns differ between high and low river flow. During high river flow, high upstream sand supply acts to aggrade the bed both inside and outside of the channel network. Erosion during high flow is focused at the sand shoals that define the sidewalls of the bifurcate channels, causing channel network rearrangement into a single primary channel with the remaining secondary channels branching off of it. During low river flow, bed erosion is focused at channel tips and the beds of all of the subaqueous distributary channels, leading to a bayward extension of each channel tip by ≥0.87 channel-widths. Channel-bottom erosion during low river flow is enhanced by tidally modulated currents that support sand suspension and transport in the subaqueous channels during ebb tide while receiving only a small sand supply from upstream. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.