Water Stewardship Information Sources
| ID | 537 |
|---|---|
| Citation | Eaton, B and Giles, T. 2008. Assessing the effect of vegetation-related bank strength on channel morphology and stability in gravel-bed streams using numerical models. Earth Surface Processes and Landforms. DOI: 10.1002/esp.1768 |
| Organization | UBC |
| URL | http://www.geo.oregonstate.edu/classes/geo582/articles_2010/Eaton_Giles_vegetation_bank_strength_ESPL_2008.pdf |
| Abstract/Description or Keywords | Bank strength due to vegetation dominates the geometry of small stream channels, but has virtually no effect on the geometry of larger ones. The dependence of bank strength on channel scale affects the form of downstream hydraulic geometry relations and the meandering-braiding threshold. It is also associated with a lateral migration threshold discharge, below which channels do not migrate appreciably across their floodplains. A rational regime model is used to explore these scale effects: it parameterizes vegetation-related bank strength using a dimensionless effective cohesion, C*. The scale eff r ects are explored primarily using an alluvial state space defined by the dimensionless formative discharge, Q*, and channel slope, S, which is analogous to the Q-S diagrams originally used to explore meandering-braiding thresholds. The analyses show that the effect of vegetation on both downstream hydraulic geometry and the meandering-braiding threshold is strongest for the smallest streams in a watershed, but that the effect disappears for Q* > 106 . The analysis of the migration threshold suggests that the critical discharge ranges from about 5 m3 /s to 50 m3 /s, depending on the characteristic rooting depth for the vegetation. The analysis also suggests that, where fires frequently affect riparian forests, channels may alternate between laterally stable gravel plane-bed channels and laterally active riffle-pool channels. These channels likely do not exhibit the classic dynamic equilibrium associated with alluvial streams, but instead exhibit a cyclical morphologic evolution, oscillating between laterally stable and laterally unstable endmembers with a frequency determined by the forest fire recurrence interval. Copyright ﾩ 2008 John Wiley & Sons, Ltd. KEYWORDS: vegetation-related bank strength; channel morphology; channel stability; gravel-bed streams; numerical models |
| Information Type | article |
| Regional Watershed | North Thompson |
| Sub-watershed if known | Fishtrap Creek |
| Aquifer # | |
| Comments | project may be resurrected in future as funding permits, Phil Owens and UNBC group still doing some work |
| Project status | complete |
| Contact Name | Brett Eaton |
| Contact Email | [email protected] |