Conditions for branching in depositional rivers

Abstract

Research Article| May 01, 2007 Conditions for branching in depositional rivers Douglas J. Jerolmack; Douglas J. Jerolmack 1Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA and National Center for Earth-surface Dynamics, University of Minnesota, Minneapolis, Minnesota 55414, USA Search for other works by this author on: GSW Google Scholar David Mohrig David Mohrig 2Jackson School of Geosciences, University of Texas at Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Douglas J. Jerolmack 1Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA and National Center for Earth-surface Dynamics, University of Minnesota, Minneapolis, Minnesota 55414, USA David Mohrig 2Jackson School of Geosciences, University of Texas at Austin, Texas 78712, USA Publisher: Geological Society of America Received: 06 Sep 2006 Revision Received: 22 Dec 2006 Accepted: 28 Dec 2006 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2007) 35 (5): 463–466. https://doi.org/10.1130/G23308A.1 Article history Received: 06 Sep 2006 Revision Received: 22 Dec 2006 Accepted: 28 Dec 2006 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Douglas J. Jerolmack, David Mohrig; Conditions for branching in depositional rivers. Geology 2007;; 35 (5): 463–466. doi: https://doi.org/10.1130/G23308A.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 It is often taken for granted that rivers organize transport into a single active channel. In some net-depositional environments, however, flow of water and sediment is distributed in several stable channels. Such branching rivers may be confined in valleys (anabranching or anastomosed) or unconfined on deltas (distributaries), and their existence confronts us with the very basic question of what governs the spatial organization of channel patterns in sedimentary landscapes. Current models for equilibrium channel morphology cannot predict the occurrence of branching rivers because they do not consider dynamical processes such as avulsion, i.e., the rapid abandonment of a channel in favor of a new path at lower elevation. The requisite conditions for avulsion have been the subject of ongoing debate. Here we resolve the conditions leading to channel avulsion, and show that branching rivers occur when avulsion is the dominant mechanism of lateral channel motion. A compilation of field and laboratory data demonstrates that avulsion frequency scales with the time required for sedimentation on channel beds to produce a deposit equal to one channel depth. From the relative rates of bank erosion and channel sedimentation, we derive a dimensionless mobility number that accurately predicts the conditions under which anabranching and distributary channels occur. Results may be directly applied to modeling landscape evolution over human and geologic time scales, and for inverting formative environmental conditions from channel deposits on Earth and other planetary surfaces. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.