Experiments on the Transportation of Suspended Sediment by Water

Citation

Vanoni, Vito August (1940) Experiments on the Transportation of Suspended Sediment by Water. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/CYT2-W932. https://resolver.caltech.edu/CaltechETD:etd-05142003-162057

Abstract

Measurements of the sediment and velocity distributions in a laboratory flume were made for various values of rate of flow, slope of channel, and size and amount of suspended load. The experimental sediment-distribution measurements were compared with the theoretical distribution which assumes that the coefficient for the turbulent transfer of suspended sediment is the same as the coefficient for the turbulent transfer of momentum.

The following are the main findings:

(1) The measured sediment distributions have the same form as the theoretical distribution but do not agree quantitatively with them, thus showing, as was anticipated, the invalidity of the assumption that the transfer coefficient for sediment was equal to that for momentum. In general the measurements gave larger concentrations than the theory when the suspended load was fine, while as the size of the sediment was increased the agreement improved up to a certain size of sediment beyond which the tendency was in the opposite direction.

(2) Suspended sediment in a flow tends to reduce appreciably the turbulent transfer of momentum and hence the resistance to flow, allowing the sediment-laden water to flow more rapidly than a comparable clear water flow. This effect increases with the total sediment load and with a decrease in the grain size of the sediment.

(3) Suspended load in a flow tends to produce instability and may be a factor in causing the secondary circulation observed in rivers.

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