FLOOD01191

• County: Statewide
• Title: Laboratory Data on Course-Sediment Transport for Bedload-Sampler Calibrations
• Date: 1/1/1987
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

These various data constitute a large body of hy.
draulic and sedimentologic infonnation on the transport of
bedload particles thai range in size from about 1.0 mm to
32.0 mm. The data are unique, not only because of the wide
range of particle sizes that were used in the invesligation,
but also because of the relatively large flow depths that were
maintained in all runs and the extent to which spatial and
temporal variations in many variables were measured. How-
ever, because suspended-sediment transport had 10 be inhib-
ited, the experimental data characterize only hydraulic and
sedimentologic conditions attendant with low to moderate
bedload.transport rates. Also, because the experimental
flume could not be tilted, a transition zone of nonunifonn
flow existed at the upper end of the channel. Stalistical
procedures had to be used to ascertain the reach of channel
where the flow could be considered unifonn.
This report explains in detail how Ihe data were col-
lected, synthesized, and organized as a data base. Because
of the large number of individual values, measured transport
rates and other kinds of data are stored on magnetic media.
Complete replications of part or all of these data are avail-
able from the U.S. Geological Survey (see Availability of
Data. inside back cover). Summaries that indicate the extent
and character of the various data sets, as well as mean values
of several common variables, are presented in tables in this
report, and selected segmenls of the data are depicted in
graphical fonn 10 illustrale Ihe magnitude and variability of
various quantities.

Acknowledgments

Funding for construction of the calibration facility and
for the sampler calibration program was provided, in a large
part. by the U.S. Environmental Protection Agency. In ad.
dition, the U.S. Anny Corps of Engineers, St. Paul District,
funded the initial designing of the facility and contributed a
mobile conveyor belt, as well as space at the Twin Cities
Anny Ammunilion Plant, New Brighton, Minn., for the
preparation of bed material. Northern States Power Co.
provided space in a spillway outside of the laboratory for
storing used bed material. The Washinglon District office of
the U.S. Geological Survey contributed some supplemental
funds. The late Dr. A.G. Anderson, Director of SAFHL.
guided the early design activity on the calibration facilily.
Dr. Anderson's enthusiasm for the facility and for the sam.
pIer calibration program provided important encouragement
for the project. After Dr. Anderson's death, the facility was
completed under the direction of Dr. R.E.A. Arndt, SAFHL
Director, and Professor John Ripkin. Mr. Loren M. Berg-
stedt, SAFHL, designed the mechanical and hydraulic fea-
tures of the facility and supervised construction. The suc-
cess of the program attests to the quality of Mr. Bergstedt's
effort. The authors sincerely appreciate the skill and dedica-
tion that the entire slaff at SAFHL devoted to the project.

BEDLOAD-SAMPLER CALIBRATION FACILITY

Mechanical elements of the bedload-circulation sys-
tem were designed and constructed by SAFHL personnel in
accordance with project specifications. The system (figs. I
and 2) was incorporated inlo the main laboratory flume,
which is a rectangular concrete channel that has a fixed
horizontal floor and which is 9 ft wide, 6 ft deep, and 272 ft
long. Flows up to about 300 ftl/s can be diverted from the
Mississippi River through a sluice gate, into a vertical en-
trance lunnel, and from there through a baffle section into
Ihe flume. Flow rale is controlled by the sluice gate, and an
adjustable sharp-crested weir at the end of the flume is used
to fix the depth of flow.

Bedload Trap and Recirculation System

The primary element of the system was an automated
sediment trap situated beneath the floor of Ihe channel. The
entrance to the trap was an adjuslable-width slot across the
full width of the channel at a position, designated station 0,
213 ft downstream from the channel enlrance and 59 ft
upstream from the weir. The slot was divided laterally into
seven 1.J.ft sections and was adjusted to an open width of
1.0 ft in the longitudinal direction. Seven box-shaped con.
tainers open at the top, called weigh pans, were located
directly below the seven slot sections (fig. 3). The weigh
pans were fitted with doors on the bottom that were opened
and closed by hydraulically actuated cylinders. Each weigh
pan operaled independently and was suspended freely by
rods thai passed vertically upward through thin struts to
triangular brackets above the channel. Each bracket, in turn.
connected to a cylindrically shaped load cell (fig. 4) that
continuously produced an output voltage proportional to Ihe
submerged weight of the weigh pan and its contents. Limit
controls caused the pan doors to open, then close, whenever
a preset voltage (weight) was reached. The weigh pans were
suspended within a hopper section that was shaped at the
bottom to fonn a tapered cylindrical channel that housed a
hydraulically driven sediment-return feeder screw (auger).
The auger discharged sediment into a sump on the outside
of the hopper (fig. 2B). The sump was connected by a short
length of 8-in. pipe to the suction side of a recessed-
impeller, materials-handling pump. A vertical, rectangular,
constant.level waler tank extended directly upward from the
sump. The discharge side of the pump connected to an 8-in.
sediment-return pipe that tenninated in an inverted Y-
shaped diffusor at the upper end of the channel. The system
was designed to continuously measure and recirculate bed-
load particles ranging in size from about I to 75 mm, at rates
as high as about 4 Iblslfl, and to discharge water diverted to
the channel back into the river.
During operation of the flume, particles transported
down the channel as bedload fell through the slot and accu-
mulated in the weigh pans, whiJe the water passed over the

2 Laboratory Data on Coarse.Sediment Transport for Bedload.Sampler Calibrations