Spatial variations in surface sediment structure in riffle–pool sequences : a preliminary test of the Differential Sediment Entrainment Hypothesis (DSEH)

Auteur(s) et Affiliation(s)



Description :
Riffle-pool sequences are maintained through the preferential entrainment of sediment grains from pools rather than riffles. This preferential entrainment has been attributed to a reversal in the magnitude of velocity and shear stress under high flows; however the Differential Sediment Entrainment Hypothesis (DSEH) postulates that differential entrainment can instead result from spatial sedimentological contrasts. Here the AA. use a novel suite of in situ grain-scale field measurements from a riffle-pool sequence to parameterize a physically-based model of grain entrainment. Field measurements include pivoting angles, lift forces and high resolution digital elevation models (DEMs) acquired using terrestrial laser scanning, from which particle exposure, protrusion and surface roughness were derived. The entrainment model results show that grains in pools have a lower critical entrainment shear stress than grains in either pool exits or riffles. Field data were collected from Bury Green Brook, Hertfordshire, England.


Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2013, vol. 38, n°. 5, p. 449-465, nombre de pages : 17, Références bibliographiques : 1 p.

Date :
2013

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