Controlling factors in the distribution and development of incised meanders in the central Colorado Plateau

Abstract

Research Article| February 01, 1990 Controlling factors in the distribution and development of incised meanders in the central Colorado Plateau DEBORAH R. HARDEN DEBORAH R. HARDEN 1Department of Geology, San Jose State University, San Jose, California 95192 Search for other works by this author on: GSW Google Scholar Author and Article Information DEBORAH R. HARDEN 1Department of Geology, San Jose State University, San Jose, California 95192 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1990) 102 (2): 233–242. https://doi.org/10.1130/0016-7606(1990)102<0233:CFITDA>2.3.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 DEBORAH R. HARDEN; Controlling factors in the distribution and development of incised meanders in the central Colorado Plateau. GSA Bulletin 1990;; 102 (2): 233–242. doi: https://doi.org/10.1130/0016-7606(1990)102<0233:CFITDA>2.3.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 A study of the distribution and geometry of incised meanders in 64 reaches encompassed approximately 600 km of the Green, Colorado, and San Juan Rivers in the central Colorado Plateau. The sinuosity, average planform size, and average cross-sectional symmetry of each reach were determined by map measurements and by spectral analysis of the curvature series for each reach, as determined from interpolations of the digitized traces of the channels. Possible controlling variables examined, including average channel gradient, drainage area, average bedrock erodibility, and bedrock structure, were compiled for each reach, using available maps. Gradients in the studied reaches are significantly correlated with bedrock type.Sinuous incised channels are generally found in low-gradient reaches. In the San Juan River, the channel is sinuous where it flows against the bedrock dip and generally straight in reaches where flow is downdip. This correlation is weak in the Green and Colorado Rivers. The average meander size of the sinuous reaches, as described by the median curvature value for each reach, is generally less in steeper reaches than in low-gradient reaches, although the relation of bend size to controlling variables is much less clear than for sinuosity or cross-section shape. Most meander cross sections in the area are relatively symmetrical, but highly ingrown forms are also present. In general, symmetric bends are associated with resistant bedrock units, whereas ingrown forms develop in massive sandstone and in highly erodible bedrock. Gradient significantly influences the distribution of ingrown bends, with asymmetric meanders concentrated in reaches of low average gradient; this correlation is stronger than that between cross-section shape and lithology itself.Incised meanders of the central Colorado Plateau are probably at least partly inherited from ancestral streams of unknown age that flowed across the area before the present canyons were cut. Correlation between meander distribution and regional structures suggests that the general location of low-gradient sinuous reaches has probably not changed during the incision of the present canyons. Incised meanders, however, are clearly able to modify their geometry in response to changes in bedrock resistance, as indicated by the strong correlation between bedrock type and cross-section symmetry. One mechanism of modification is abandonment of bends, which is documented by 18 cutoff meanders in the study area. 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.