Assessing the effect of vegetation-related bank strength on channel morphology and stability in gravel-bed streams using numerical models

Auteur(s) et Affiliation(s)



Description :
Bank strength due to vegetation dominates the geometry of small stream channels, but has virtually no effect on the geometry of larger ones. A rational regime model is used to explore the scale effects: it parameterizes vegetation-related bank strength using a dimensionless effective cohesion, Cr. 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.


Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2009, vol. 34, n°. 5, p. 712-724, nombre de pages : 13, Références bibliographiques : 1,5 p.

Date :
2009

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley