News Release
U.S. Department of Interior
U.S. Geological Survey
Wyoming District
Release Internet location of release June 18, 1998 http://wy.water.usgs.gov/news/archives/061898b.htm Contact Address District Chief 2617 E. Lincolnway, Ste. B Public Information Officer Cheyenne, WY 82001-5662 E-mail Phone Fax state_rep_wy@usgs.gov (307)778-2931 (307)778-2764
USGS REPORTS RESEARCH ON SEDIMENT TRANSPORT
It isn't easy to measure the rate at which a river transports its bedload--the sand, gravel, and larger sediment particles rolling or bouncing along the river bed. How do you gather the sediment? One way is to dig a trough all the way across the river channel so that all bedload particles passing the site will fall into the trough. Next, line the trough with concrete and add a system of conveyor belts, hoppers, and scales, to raise the sediment caught in the trough to the surface, weigh it, and return it to the channel downstream. During the 1970s scientists of the U.S. Geological Survey (USGS), U.S. Department of the Interior, operated such an apparatus at a site in northwestern Wyoming. It is the only bedload trap in the world known to have worked successfully.A new USGS publication, "Bedload and River Hydraulics--Inferences from the East Fork River, Wyoming, " describes the geologic and hydrologic setting at the research site, why the site was chosen, how the trap was designed and operated, and the significance of the research findings. The bedload measurement data and supporting observations and interpretations are included. Released as USGS Professional Paper 1583, the extensively illustrated report was written by Luna B. Leopold, Emeritus Professor of Geology at the University of California, Berkeley and former Chief Hydrologist, USGS; and William W. Emmett, a USGS Research Hydrologist, now retired.
Designed by Leopold, the unique apparatus was constructed at a site on the East Fork River in Sublette County, Wyoming, about 17 miles southeast of the town of Pinedale. During operation of the trap, bedload particles fell into the 48-foot wide trough through eight independently operated gates (trap doors). The particles were transported laterally by one conveyor belt and raised to the surface by another, where they were weighed automatically and returned to the river downstream by other conveyor belts. River stage, river flow, particle size, and other variables needed to analyze bedload transport also were measured.
The Bedload Trap on the East Fork River
From the mid-1960s to the 1980s, research at the bedload trap on the East Fork was the centerpiece of numerous studies of the complex relationships between river flow, bedload transport, channel configuration, and other river characteristics along the river. The studies resulted in approximately 40 scientific reports.
The methods and results of the research on the East Fork have received worldwide scientific attention. The characteristics of bedload transport determined from direct measurement of the entire load of sand and gravel carried by a river can be used to evaluate results of other sampling and computational methods.
Leopold and Emmett point out that understanding the natural processes of bedload transport is important for evaluating past or future human modifications of rivers. Most of the sediment transported by a river consists of silt and clay particles, which are carried long distances in suspension. It is the coarser particles, however--sand and gravel moving short distances as bedload--that, together with water discharge, determine the physical characteristics of a river, such as the width, depth, and bed elevation of the channel, and the velocity of the flowing water.
Copies of U.S. Geological Survey Professional Paper 1583 may be purchased from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, Colorado 80225 for $10.00 per copy. When ordering, please use report number and complete title. Prepayment is required by check or money order, made payable to: U.S. Department of the Interior--USGS
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