The linkage between velocity patterns and sediment entrainment in a forced-pool and riffle unit

Auteur(s) et Affiliation(s)

THOMPSON, D.M.

Dep. of Physics, Astronomy and Geophysics, Connecticut College, New London, Etats-Unis

WOHL, E.E.

Dep. of Physics, Astronomy and Geophysics, Connecticut College, New London, Etats-Unis

Description :
Three-dimensional velocities and turbulence intensities were measured with an acoustic Doppler velocimeter at 222 different points at 3 similar flows within a large pool-riffle unit on North Saint Vrain Creek, Colorado. Sediment-sorting patterns were observed with the introduction of 500 tracer particles painted according to initial seeding location. Tracer particles moved sporadically during a 113 day period in response to the annual snowmelt peak flow. Velocity data indicate high instantaneous velocities and turbulence levels in the centre of pools. Patterns of sediment deposition support the notion that stream competence is higher in the pool than the downstream riffle. Flow convergence around a large channel constriction appears to play a major role in multiple processes. Jet flow, flow separation, vortex scour and turbulence generation enhance scour in the centre of pools. Ultimately, multiple processes appear to play some role in maintenance of this forced pool and the associated riffle.

Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2009, vol. 34, n°. 2, p. 177-192, nombre de pages : 16, Références bibliographiques : 1,5 p.

Date :
2009

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

Langue :
Anglais