Repository logo
 

Flume studies of the transport of pebbles and cobbles on a sand bed

Date

1961-12

Authors

Fahnestock, Robert K., author
Haushild, W. L., author
Colorado State University, U.S. Geological Survey, publisher

Journal Title

Journal ISSN

Volume Title

Abstract

During experiments on sediment transport and resistance to flow with a uniform 0.33 mm sand, data were taken on the movement of individual rocks having intermediate diameters from about 0.1 to 0.5 foot. The experiments were conducted in a flume 2-foot wide by 80-feet long and for most runs, depth was held constant at 0.5 feet. The experiments showed that rocks on sand bed moved downstream consistently only if the flow was in the upper regime; that is, only if the bed forms were plain bed, standing waves, or antidunes. The rocks moved at velocities that were approximately one half of the average veloc1ty of the water. With all bed forms in the lower flow regime (ripples, ripples superimposed upon dunes, and dunes), the rocks always moved upstream and down into the bed. That is, the rocks moved into a scour pocket that formed at the upstream side of the rock. The movement upstream and down into the bed is limited by and approximately equal to the distance below the original rock position of the minimum bed elevation plus approximately one-half the rock diameter. The data indicate that cross bedded sand deposits formed by the ripple or dune phases of transport would contain few, if any, pebbles or cobbles. Because of the flow, in at least the downstream reaches of most rivers is in the lower regime, the upstream movement and scour into the bed demonstrated in the experiment is an important factor in the sorting process.

Description

CER61RKF80.
December 1961.
Includes bibliographical references.
Submitted to the Bulletin of Geological Society of America for publication.

Rights Access

Subject

Sediment transport
Flumes -- Models
Bed load

Citation

Associated Publications