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Laboratory Data on Coarse-Sediment Transport for Bedload-Sampler Calibrations By D.W. Hubbell, H.H. Stevens, Jr., J.V. Skinner, and J.P. Beverage Abslract A unique facility capable of recirculating and continu- ously measuring the transport rates of sediment particles rang- ing in size from about 1 to 75 millimeters in diameter was designed and used in an extensive program involving the cali- bration of bedload samplers. The facility consisled of a 9.fool- wide by 6-fool-deep by 272-foot.long rectangular channel that incorporated seven automated collection pans and a sediment. return system. The collection pans accumulated, weighed, and periodically dumped bedload falling through a slot in the chan- nel floor. Variations of the Helley-Smith bedload sampler, an Arnhem sampler, and two VUV.type samplers were used to obtain transport rates for comparison with rates measured at the bedload slot (trap). Tests were conducted under 20 differenl hydraulic and sedimentologic conditions (runs) wilh 3 uniform-size bed materials and a bed-material mixture. Hy- draulic and sedimentologic data collected concurrently with the calibration measurements are described and, in part, sum- marized in tabular and graphic form. Tables indicate the extent of the data, which are available on magnetic media. The infor. mati on includes sedimenHransport rates; particle.size distri. butions; water discharges, depths, and slopes; longitudinal profi les of streambed.surface elevations; and temporal records of streambed.surface elevations at fixed locations. INTRODUCTION In 1979, the U.S. Geological Survey began the data- collection phase of a comprehensive laboratory investiga- tion to evaluate and calibrate several different types of bed- load samplers. The study was conducted at the St. Anthony Falls Hydraulic Laboratory (SAFHL), University of Minne- sota, in a large flume that had been modified to house a unique system for circulating bedload and continuously measuring the rate of bedload transport. In addition, other equipment systems were installed to facilitate the continu- ous monitoring and the rapid and accurate periodic measur- ing of various hydraulic and sedimentologic variables perti- nenl to tbe study. Because of current interest in the Helley-Smith bed. load sampler (Helley and Smith, 1971; Druffe! and others, 1976; Emmett, 1980), the principal effort of the investiga- tion was directed toward testing and evaluating full.scale variations of this type of sampler; six variations were exam- ined to evaluate the effect of different nozzle expansions and entrance widths. Additionally, an Ambem sampler (Water- loopkundig Lahoratorium, 1949) was tested under several different conditions, and two versions of the VUV sampler (Novak, 1957) were tested to a limited extent. During the investigation, 4 different bed materials were placed in the flume, and runs were made under 20 separate stationary hydraulic and sedimentologic condi. tions. Three of the bed materials were composed of particles that had been sieved to yield nearly uniform materials hav- ing median particle diameters of 2.1 mm (5 runs), 6.5 mm (6 runs), and 23.5 mm (5 runs). The fourth bed material was artificially created by combining prescribed proportions of the uniform materials to yield an approximately log-normal size distribution of particles from 1.4 to 32.0 mm (4 runs). Because of particle attrition due to fracturing within the system during the first three runs with the uniform 23.5-mm bed material, the size gradation of the bed material during the fourth run was analogous to that of a mixture; newly sieved 23.5-mm material was installed to replace the nonuniform material for the fifth run. The test runs were made in the following order: 6.5-mm bed material, 2.1-mm material, 23.5.mm bed material, and mixed bed material. As many as six different samplers were used in each run to collect bedload samples for evaluating and calibrating the individual samplers. Except for several runs involving the Arnhem sampler, between 60 and 120 samples usually were collected by each sampler during each run to define sampled rates. Short-duration bedload-transport rates meas- ured by the automated weigh pans were obtained during each run for comparison with the sampled rates. In addition to measurements of bedload transport, data were collected continuously on water discharge and on streambed-surface elevations, near the centerline of the flume, at several longitudinal positions. Also, periodically, longitudinal profiles of streambed-surface elevation and water-surface elevation were defined concurrently through- out the experimental reach. Samples of material from the streambed and from the weigh pans were collected for particle-size analysis periodically during runs; additional samples were collected at the outlet of the sediment-return line during runs with the bed.material mixture. Introduction 1