Evaluating competing hypotheses for the origin and dynamics of river anastomosis

Auteur(s) et Affiliation(s)

KLEINHANS, M.G.

Fac. of Geosciences, Dep. of Physical geography, Univ., Utrecht, Pays-Bas

DE HAAS, T.

Fac. of Geosciences, Dep. of Physical geography, Univ., Utrecht, Pays-Bas

LAVOOI, E.

Fac. of Geosciences, Dep. of Physical geography, Univ., Utrecht, Pays-Bas

MALASKE, B.

Alterra, Univ. and Research Centre, Wageningen, Pays-Bas

Description :
The AA. test hypotheses on morphodynamic scenario modelling and data of the upper Columbia River. Initial and boundary conditions for the modelling were derived from field data. A 1D network model was built based on gradually varied flow equations, sediment transport prediction, mass conservation, transverse slope and spiral meander flow effects at the bifurcations. The number of channels and crevasse splays decreases in a downstream direction. These observations concur with bed sediment overloading from upstream, which can have caused channel aggradation above the surrounding floodplain and subsequent avulsion. The modelling also indicates that avulsion was likely caused by upstream overloading. In the model, multi-channel systems inevitably evolve towards single-channel systems within centuries because symmetric channel bifurcations are inherently unstable. The AA. conclude that this anastomosing pattern is the result of time-varying sediment overloading and is not an equilibrium pattern feature.

Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2012, vol. 37, n°. 12, p. 1337-1351, nombre de pages : 15, Références bibliographiques : 30 ref.

Date :
2012

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

Langue :
Anglais