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Laboratory experiments on erosion and deposition of loess by laminar sheet flow and turbulent rill flow in Comptes rendus = Proceedings.

Auteurs :
SAVAT, J.
VOGT, H.
VOGT, T.
Ministère des Universités. Université Louis-Pasteur, Institut de Géographie. Strasbourg
Ministère de l'Agriculture. Institut national de la Recherche agronomique, Station d'agronomie de Colmar. (INRA). Colmar

Description :
Laboratory experiments with a recirculating flume have demonstrated that rills can only be dug into an originally smooth surface when the Froude number of the laminar flow exceeds 1.4. From that critical limit on the net drag onto the sandy grains may suffice to initiate a rolling movement if the grains protrude into the faster upper flow laminar. This latter condition depends on the cohesion of the loess| indeed the sand grains sink into a thoroughly wetted cohesionless loess. Simulated rainfall always increases the transporting capacity of the laminar flow. Even small amounts of wash-load increase the viscosity by 30 percent. Due to the effect of cohesion the bed-load carried by the laminar sheet flow is always smaller than the amount predicted by the equation of Yalin. On steep slopes exceeding 10 the pushing effect of the drag results in a downslope evolution of the created rills. (the A.).


Type de document :
Congrès

Source :
Colloque sur l'érosion agricole des sols en milieu tempéré non méditerranéen=Seminar on agricultural soil erosion in temperate non mediterranean climate, 1979, p. 139-143

Date :
1979

Editeur :
Pays édition : Inconnu

Langue :
Anglais
Droits :
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