Robert H. Webb David W. Hyndman John R. Gray 1991 <p>In support of beach-stability research, bedload and suspended sediment were measured during a steady flow of 5,880 ft³/s and receding flows from 12,100 to 5,660 ft³/s in the Colorado River above National Canyon, near Supai, Arizona, October 7-12, 1989. During steady flows, 75 percent of the mean total-sediment discharge of 128 t/d was in suspension and about half the total-sediement load was finer than 0.062 mm. Median grain sizes of bedload and bed material were 0.43 and 0.40 mm, respecively. Although steady-flow bedload transport varied from the mean by about 45 percent, suspended-sediment discharge remained constant within sampling error. Helley-Smith and BL-86-3 bedload samplers were not significantly different. At larger transport rates, however, the rates measured by the Helley-Smith exceeded those measure by the BL-86-3. Transport rates from bedload samples collected with Helley-Smith and BL-86-3 bedload samplers in sections 8 ft apart demonstrate no consistent autocorrelation or cross correlation. Cross-sectional bedload-transport rates measured concurrently or consecutively with the bedload samplers showed good agreement indicating that bedload varied by at least a factor of 2.4 during the steady-flow period. Ninety-five percent of the bedload transport during low flow occurred in the center one-third of the channel.</p> application/pdf en U.S. Geological Survey Low-flow sediment transport in the Colorado River text