Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (14) Citing Articles via Google Scholar Google Scholar Articles by Allmendinger, N. E. Articles by Hession, W. C. Search for Related Content GeoRef GeoRef Citation

The influence of riparian vegetation on stream width, eastern Pennsylvania, USA

Nicholas E. Allmendinger^,1, James E. Pizzuto^,2, Noel Potter, Jr.^,3, Thomas E. Johnson^#,4 and W. Cully Hession^,5

¹ Department of Geosciences and Natural Resource Management, Western Carolina University, Cullowhee, North Carolina 28723, USA
² Department of Geology, University of Delaware, Newark, Delaware 19716, USA
³ Department of Geology, Dickinson College, P.O. Box 1773, Carlisle, Pennsylvania 17013, USA
⁴ Patrick Center for Environmental Research, Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103, USA
⁵ Department of Civil and Environmental Engineering, University of Vermont, Burlington, Vermont 05405, USA

We surveyed adjacent reaches with differing riparian vegetation to explain why channels with forested banks are wider than channels with nonforested banks. Cross sections and geomorphic mapping demonstrate that erosion occurs at cutbanks in curving reaches, while deposition is localized on active floodplains on the insides of bends. Our data indicate that rates of deposition and lateral migration are both higher in nonforested reaches than in forested reaches. Two dimensionless parameters, and E, explain our observations. represents the influence of grassy vegetation on rates of active floodplain deposition; it is 5 times higher in nonforested reaches than in forested reaches. E is proportional to rates of cutbank migration; it is 3 times higher in nonforested reaches than in forested reaches. Differences in width between forested and nonforested reaches are proportional to E/. In forested reaches, channels are wide with banks that are difficult to erode. Dense tree roots create a low value of E, and the channel migrates slowly. E/ is high, however, because is very low: shade from trees inhibits the growth of grass on active floodplains. In nonforested reaches, channels are narrow with banks that are easy to erode. E is high, and the channel migrates rapidly. E/ is low, however, due to a very large value of : grass grows readily on nonforested convex bank floodplains. Thus, differences in width between forested and nonforested reaches are related to a balance between rates of cutbank erosion and rates of deposition on active floodplains, implying that equilibrium widths develop to equalize rates of cutbank erosion and vegetation-mediated rates of deposition on active flood-plains. These results suggest that accurate models of width adjustment should consider the combined effects of bank erodibility and floodplain depositional processes, rather than focusing on these processes in isolation from one another.

Key Words: riparian vegetation • floodplains • bank erosion • hydraulic geometry • width

This article has been cited by other articles:

				A. D. Howard How to make a meandering river PNAS, October 13, 2009; 106(41): 17245 - 17246. [Full Text] [PDF]

				J. Pizzuto and M. O'Neal Increased mid-twentieth century riverbank erosion rates related to the demise of mill dams, South River, Virginia Geology, January 1, 2009; 37(1): 19 - 22. [Abstract] [Full Text] [PDF]