Threshold of critical power in streams

Abstract

Research Article| May 01, 1979 Threshold of critical power in streams WILLIAM B. BULL WILLIAM B. BULL 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1979) 90 (5): 453–464. https://doi.org/10.1130/0016-7606(1979)90<453:TOCPIS>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation WILLIAM B. BULL; Threshold of critical power in streams. GSA Bulletin 1979;; 90 (5): 453–464. doi: https://doi.org/10.1130/0016-7606(1979)90<453:TOCPIS>2.0.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract Stream power is the power available to transport sediment load, and it may be defined as γQS, where γ is specific weight of water, Q is stream discharge, and S is slope. Critical power is the power needed to transport sediment load. The threshold of critical power is where stream power/critical power = 1.0. Where stream power exceeds critical power during long time spans, additional sediment load is obtained by vertical erosion that cuts V-shaped cross-valley profiles in bedrock. The threshold is approached asymptotically during downcutting, and high-order streams approach the threshold more rapidly than do low-order streams. High discharges cause net lateral erosion in reaches near the threshold. Straths and flood plains form under such conditions. Where stream power is less than critical power, selective bedload sedimentation decreases sediment load and size and therefore the critical power. Such deposition is self-enhancing because of concurrent decreases in slope. Thus, it is unlikely that aggrading reaches attain the threshold, but the tendency to attain the threshold may keep stream and critical power roughly the same. Reaches of streams at the critical-power threshold are sensitive to changes in climate, base level, and the impact of humans; these may change stream and/or critical power and result in aggradation or degradation. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.