Controls on the channel width of rivers: Implications for modeling fluvial incision of bedrock

Abstract

Research Article| March 01, 2005 Controls on the channel width of rivers: Implications for modeling fluvial incision of bedrock Noah J. Finnegan; Noah J. Finnegan 1Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar Gerard Roe; Gerard Roe 1Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar David R. Montgomery; David R. Montgomery 1Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar Bernard Hallet Bernard Hallet 1Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar Geology (2005) 33 (3): 229–232. https://doi.org/10.1130/G21171.1 Article history received: 10 Sep 2004 rev-recd: 19 Nov 2004 accepted: 26 Nov 2004 first online: 02 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 Noah J. Finnegan, Gerard Roe, David R. Montgomery, Bernard Hallet; Controls on the channel width of rivers: Implications for modeling fluvial incision of bedrock. Geology 2005;; 33 (3): 229–232. doi: https://doi.org/10.1130/G21171.1 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 On the basis of the Manning equation and basic mass conservation principles, we derive an expression for scaling the steady-state width (W) of river channels as a function of discharge (Q), channel slope (S), roughness (n), and width-to-depth ratio (α): W = [α(α + 2)2/3]3/8Q3/8S−3/16n3/8. We propose that channel width-to-depth ratio, in addition to roughness, is a function of the material in which the channel is developed, and that where a river is confined to a given material, width-to-depth ratio and roughness can be assumed constant. Given these simplifications, the expression emulates traditional width-discharge relationships for rivers incising bedrock with uniformly concave fluvial long profiles. More significantly, this relationship describes river width trends in terrain with spatially nonuniform rock uplift rates, where conventional discharge-based width scaling laws are inadequate. We suggest that much of observed channel width variability in river channels confined by bedrock is a simple consequence of the tendency for water to flow faster in steeper reaches and therefore occupy smaller channel cross sections. We demonstrate that using conventional scaling relationships for channel width can result in underestimation of stream-power variability in channels incising bedrock and that our model improves estimates of spatial patterns of bedrock incision rates. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.