Oscillations in arid alluvial-channel geometry

Abstract

Research Article| August 01, 2004 Oscillations in arid alluvial-channel geometry Jon D. Pelletier; Jon D. Pelletier 1Department of Geosciences, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Stephen DeLong Stephen DeLong 1Department of Geosciences, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Jon D. Pelletier 1Department of Geosciences, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, USA Stephen DeLong 1Department of Geosciences, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, USA Publisher: Geological Society of America Received: 29 Jan 2004 Revision Received: 13 Apr 2004 Accepted: 18 Apr 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2004) 32 (8): 713–716. https://doi.org/10.1130/G20512.1 Article history Received: 29 Jan 2004 Revision Received: 13 Apr 2004 Accepted: 18 Apr 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 Jon D. Pelletier, Stephen DeLong; Oscillations in arid alluvial-channel geometry. Geology 2004;; 32 (8): 713–716. doi: https://doi.org/10.1130/G20512.1 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 Arid alluvial channels on piedmonts and valley floors often exhibit an oscillating pattern of narrow, deeply incised reaches and wide, shallow reaches with a characteristic wavelength. How do these oscillations develop and what controls their wavelengths? To address these questions we developed a two-dimensional numerical model that couples erosion and deposition in a channel bed with cross-sectional widening and narrowing. This model is inherently unstable over a range of spatial scales dependent on the channel width, depth, and slope. In the initial phase of model evolution, wider-than-average channel reaches become zones of distributary flow that aggrade, lose stream power, and further widen in a positive feedback. Simultaneously, narrower-than-average reaches incise, gain stream power, and further narrow. In the second stage of model evolution, this instability is balanced by the diffusive nature of longitudinal profile evolution, and solitary topographic waves propagate in the upstream direction with a characteristic wavelength and amplitude. The model predicts a specific quantitative relationship between the oscillation wavelength and channel width, depth, and slope that is verified by a database of channel geometries in southern Arizona. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.