Wednesday, July 27, 2011

Sandbar experiment downstream of Glen Canyon Dam

The USGS has published results of the most recent high flow experiments on the Colorado River to rebuild sand bars below Glen Canyon Dam. They found that "Each of the controlled floods resulted in sandbar deposition that was followed by erosion in the 6-month post-flood period. Erosion rates are positively correlated with post-flood dam release volumes and negatively correlated with post-flood tributary sediment supply volume."

[right, "typical eddy sandbar and adjacent channel showing pattern of recirculating flow, the reference stage of 227 m3/s in white, and a typical backwater “closure” line in red. The portion of the sandbar above the reference stage and below the reference stage is illustrated. Mainstem flow is from bottom right to top left." Credit, USGS]

Ref: GEOMORPHIC RESPONSE OF SANDBARS TO THE MARCH 2008 HIGH-FLOW EXPERIMENT ON THE COLORADO RIVER DOWNSTREAM FROM GLEN CANYON DAM, Paul E. Grams, et al, 2nd Joint Federal Interagency Conference, Las Vegas, NV, June 27 - July 1, 2010

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