| Abstract: | Bedload transport was measured with two sampler types (vortex tube and Helley-Smith pressure differential) for three major storms at Flynn Creek, which drains a 2.2-km2 forested watershed in the Oregon Coast Range. The largest flow during two winters of monitoring had a peak discharge of 0.79 m3 s-1 km-2, with an associated recurrence interval of ? 1.3 yr. The median particle diameter of sediment in transport was generally < 1 mm. The vortex tube and its associated sample box were relatively inefficient at trapping particles < 10 mm in diameter; however, even after transport rates were adjusted to account for sampling deficiencies of the sample box, they still averaged 42–47 percent of those obtained with the Helley-Smith sampler. Organic matter and sand sized sediments in transport also were observed to partially plug the 0.2-mm-mesh bag of the Helley-Smith sampler. Large temporal variability in bedload transport rates was measured during periods of high flow. |
