8259

• UCREFRP Catalog Number: 8259
• Author: Kircher, J. E.
• Title: Sediment Transport and Source Areas of Sediment and Runoff, Big Sandy River Basin, Wyoming.
• USFW Year: 1982.
• USFW - Doc Type: Water-Resources Investigations 81-72,
• Copyright Material: NO

SEDIMENT TRANSPORT
Source of Sediment Transport
In general, there are two sources of sediment transported by a
stream: (1) The streambed material, and (2) the wash load, which is fine
material that comes from the banks and upstream parts of the watershed.
Both materials come from the watershed; however, a distinction between
them is important because bed-material transport is limited by the trans-
port capability of the stream and is functionally related to measurable
hydraulic variables, while the wash load is not. Instead, the wash load
depends on the availability of fine material (Richardson and others,
1975).
Mode of Sediment Transport
Sediment particles are transported by rolling or sliding on the bed
(bedload) or by suspension in the water by the turbulence of the stream
(suspended-sediment load). Just as there is no sharp distinction between
bed-material discharge and wash load, there is no sharp distinction
between bedload and suspended-sediment load. A particle may move part of
the time in contact with the bed and at other times be suspended by the
flow (Richardson and others, 1975).
Suspended-Sediment Load
For this study, suspended sediment was sampled with standard depth-
intergrating samplers described by the U.S. Interagency Committee on
Water Resources, Subcommittee on Sedimentation (1963). Samples were
collected at 15 to 20 verticals to determine the average concentration
and particle-size distribution of the sediment in the streamflow. Sam-
ples of suspended sediment include particles transported in the depth
interval between the surface and a point 0.3 or 0.5 foot above the bed,
depending on the sampler used (fig. 16).
Suspended-sediment samples were collected by the author at six sites
in the Big Sandy River basin. Data from these samples supplemented data
collected during previous years by the U.S. Geological Survey to define
relations between sediment concentration and water discharge.
Suspended sediment is related to the amount of water available for
transport of the material. In general, larger concentrations occur with
larger streamflows.
Concentration of suspended sediment in a stream can generally be
related to water discharge by the equation:
S
C =pQ?
where:
Cs = concentration, in milligrams per liter;
Q = streamflow, in cubic feet per second; and
p and j = regression coefficients.
(4)
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