Laserfiche WebLink
<br />Proceedings of the Seventh Federal Interagency SedimentatiQll Conference. March 25 to 29, 2001. Reno. Nevada <br /> <br />. <br /> <br />sand was 0.45 mm (as measured with a pipe dredge). At the Grand Canyon gage, the discharge <br />of water during the measurement period was approKimately 595 rrf/s [20,800 cfs] and the <br />median size of the bed sand was 0.42 mm. At the Lower Marble Canyon gage, bedload involved <br />in bedform migration was only 0.3% of the total sand load; at the Grand Canyon gage, bedload <br />was approximately 5% of the total sand load. <br /> <br />Other observations: In addition to allowing accurate measurements of bedload transport, <br />rotating side-scan sonar provides information about dune orientation relative to flow; cross- <br />channel differences or similarities in transport rate; cross-channel differences in bedform size, <br />migration speed, and migration direction; migration of superimposed dunes over larger <br />bedforms; changes through time in bedforms and sediment transport; and bedform interactions <br />such as splitting and merging. Rotating sonar is also useful in detecting starved bedforms <br />migrating over a cobble bed: individual cobbles appear and disappear as they are exposed and <br />then buried by troughs and crests of the migrating dunes. <br /> <br />REFERENCES <br /> <br />Rubin, D. M., and Hunter, R.E., 1982, Bedform climbing in theory and nature. Sedimentology. <br />29, 121-138. <br /> <br />. <br /> <br />Rubin, D. M., McCulloch, D. S., and Hill, H. R., 1983, Sea-floor-mounted rotating side-scan <br />sonar for making time-lapse sonographs. Continental Shelf Research 1,295-301. <br /> <br />Simons, D. B., Richardson, E.V., and Nordin, C.F., Jr., 1965, Bedload equations for ripples and <br />dunes. U.S. Geological Survey Professional Paper 462-H, 9 p. <br /> <br />Contact: <br />David M. Rubin <br />Coastal and Marine Geology <br />USGS Pacific Science Center <br />University of California at Santa Cruz <br />1156 High Street <br />Santa Cruz, CA 95064 <br />831-459-3156 <br />drubin@usgs.gov <br />http://walrus. wr.usgs.gov/seds/ <br /> <br />. <br /> <br />III - 143a <br />