Bank pull or bar push: What drives scroll-bar formation in meandering rivers?

Abstract

Research Article| April 01, 2014 Bank pull or bar push: What drives scroll-bar formation in meandering rivers? Wietse I. van de Lageweg; Wietse I. van de Lageweg Faculty of Geosciences, Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, Netherlands Search for other works by this author on: GSW Google Scholar Wout M. van Dijk; Wout M. van Dijk Faculty of Geosciences, Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, Netherlands *Current address: Department of Geography, Durham University, South Road, Durham DH1 3LE, UK. Search for other works by this author on: GSW Google Scholar Anne W. Baar; Anne W. Baar Faculty of Geosciences, Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, Netherlands Search for other works by this author on: GSW Google Scholar Jantien Rutten; Jantien Rutten Faculty of Geosciences, Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, Netherlands Search for other works by this author on: GSW Google Scholar Maarten G. Kleinhans Maarten G. Kleinhans † Faculty of Geosciences, Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, Netherlands †E-mail: M.G.Kleinhans@uu.nl. Search for other works by this author on: GSW Google Scholar Geology (2014) 42 (4): 319–322. https://doi.org/10.1130/G35192.1 Article history received: 09 Oct 2013 rev-recd: 12 Jan 2014 accepted: 15 Jan 2014 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 Wietse I. van de Lageweg, Wout M. van Dijk, Anne W. Baar, Jantien Rutten, Maarten G. Kleinhans; Bank pull or bar push: What drives scroll-bar formation in meandering rivers?. Geology 2014;; 42 (4): 319–322. doi: https://doi.org/10.1130/G35192.1 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 One of the most striking features of meandering rivers are quasi-regular ridges of the point bar, evidence of a pulsed lateral migration of meander bends. Scroll bars formed on the inner bend are preserved on the point-bar surface as a series of ridges as meanders migrate, and in the subsurface of the point bar as inclined heterolithic stratification with lateral accretion surfaces. It is necessary to understand the formation and sedimentary architecture of these point bars, which are fundamental geomorphic building blocks of meandering rivers and potential reservoirs for water, oil, and gas. However, it remains unresolved whether the scroll-bar pattern forms in response to outer bend bank erosion during floods (i.e., bank pull), or is forced by bank progradation (i.e., bar push). Here we use experimentally formed meandering rivers with a set of static and migrating bends to isolate the effects of sediment supply to the point bar, bank protection, and forced bank retreat. We find that channel widening caused by bank retreat near the bend apex causes deposition of new scroll ridges along the inner bend point bar, whereas scroll bars cannot be forced by sediment pulses. Thus channel width variations along meander bends cause bank pull, which is necessary for scroll-bar formation. Furthermore, we find that each newly attached scroll bar overlies a nonpermeable layer of finer grained sediment caused by the temporary flow expansion, which explains the fining-upward tendency of point bars. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.