Figure 2. Reworking of sand from a modern flood deposit into an aeolian dune; example from Grand Canyon after the 2008 controlled flood. (A) Photograph taken three weeks after the controlled flood, on April 5, 2008. Arrow indicates local prevailing wind direction. Black dashed line indicates the recent flood stage (1,160 m3/s). In the foreground is a fluvial sandbar augmented by the controlled flood (person standing on sandbar for scale). Above and downwind of the sandbar is an aeolian dune field with dunes as tall as 10 m. Location and orientation of the photograph in (B) are shown at the right side of (A). Line (A–A') shows location of topographic profiles in (C). (B) Photograph taken July 29, 2008, showing a new aeolian dune that formed along the margin of the 2008 flood deposit. (C) Topographic profiles along A–A'. In March 2008 a large sandbar formed during the controlled flood; dashed horizontal line indicates the 1,160 m3/s flood stage. Between February and October 2008 the flood sand was reworked by wind, forming the new aeolian dune of (B). By October 2009, the new dune had migrated inland above the controlled-flood elevation, and as of October 2012 the new dune was still migrating inland. Data courtesy of Northern Arizona University.
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