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The role of geology in sediment supply
and bedload transport patterns in coarse-grained streams
Ryan, Sandra E. 2007. The role of geology in sediment supply and bedload transport patterns in coarse-grained streams. In: Furniss, M.; Clifton, C.; Ronnenberg, K. eds. Advancing the Fundamental Sciences: Proceedings of the Forest National Earth Sciences Conference, San Diego, CA, 18-22 October 2004. Gen. Tech. Rep. PNW-GTR-689. Portland, OR: U.S. Forest Service, Pacific Northwest Research Station. p. 383-390
This paper compares gross differences in rates of bedload sediment moved at bankfull discharges in 19 channels on national forests in the Middle and Southern Rocky Mountains. Each stream has its own "bedload signal," in that the rate and size of materials transported at bankfull discharge largely reflect the nature of flow and sediment particular to that system. However, when rates of bedload transport were normalized by dividing by the watershed area, the results were similar for many sites. Typically, streams exhibited normalized rates of bedload transport between 0.001 and 0.003 kg s-1 km-2 at bankfull discharges. Given the inherent difficulty of obtaining a reliable estimate of mean rates of bedload transport, the relatively narrow range of values observed for these systems is notable. While many of these sites are underlain by different geologic terrane, they appear to have comparable patterns of mass wasting contributing to sediment supply under current climatic conditions. There were, however, some sites where there was considerable departure from the normalized range of values. These sites typically had different patterns and qualitative rates of mass wasting, either higher or lower, than observed for other watersheds. The gross differences in sediment supply to the stream network have been used to account for departures in the normalized rates of bedload transport observed for these sites. The next phase of this work is to better quantify the contributions from hillslopes to help explain variability in the normalized rate of bedload transport.
Keywords: bedload transport, sediment supply, mass wasting
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Publications: The role of geology in sediment supply and bedload
transport patterns in coarse-grained streams
Electronic Publish Date: April 8, 2009
Last Update: April
8, 2009