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In river valleys, fluvial and upland landscapes are intrinsically linked through sediment exchange between the active channel, near-channel fluvial deposits, and higher elevation upland deposits. During floods, sediment is transferred from channels to low-elevation nearchannel deposits [Schmidt and Rubin, 1995]. Particularly in dryland river valleys, subsequent aeolian reworking of these flood deposits redistributes sediment to higher elevation upland sites, thus maintaining naturallyoccurring aeolian landscapes [Draut, 2012].
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Alluvial sandbars occur in lateral recirculation zones (eddies) along the Colorado River in Grand Canyon National Park (Schmidt, 1990). Resource managers periodically release controlled floods from the upstream Glen Canyon Dam to rebuild these bars (Grams et al., 2015), which erode during fluctuating dam releases, and by hillslope runoff and wind deflation (Hazel et al., 2010). Because the dam blocks upstream sediment, episodic floods from tributaries provide the only supply to replace eroded sand; and much of this sand originates from a single tributary (Topping et al., 2000). Here, we present new evidence for the downstream translation of the sand component of these sediment inputs as discontinuous sand pulses....
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The flow (Wright and Kaplinski, 2011), suspended sediment transport (Topping et al., 2000), sediment storage (Grams et al., 2013), and sedimentology of sandbars (Rubin et al., 1998) of the 250 miles of the Colorado River that run through Grand Canyon National Park have been well studied and described. However, there has been little systematic or synoptic description of the morphologies and sedimentology of the riverbed, where at least 80 percent of the active sand occurs (Grams et al., 2013). Here, we use high-resolution bathymetric and backscatter measurements collected with multibeam echosounder to comprehensively describe the morphology, sedimentology, and kinematics of sand dunes, and to estimate bedload sediment...
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