Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

Schmidt, John C.; Graf, Julia B.

doi:10.3133/pp1493

Cited by 94 publications

(35 citation statements)

References 8 publications

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“…First, as expected, the dominant link between flow structures and morphodynamics for our sites is the development of sandbars within the lateral recirculation zones. This link has been noted in other settings, such as sharply curved meander bends [ Hodskinson and Ferguson , 1998] and groyne fields [ Sukhodolov et al , 2002], and has been studied extensively in Grand Canyon by Schmidt [1990], Schmidt and Graf [1990], Rubin et al [1990], and Schmidt et al [1993], among others. Fine sediment deposition occurs in these zones due to flow deceleration around the reattachment point and due to weak secondary circulation or stagnant flow immediately downstream from the separation point, leading to two distinct deposits termed reattachment and separation sandbars [ Schmidt , 1990, Figure 2].…”

Section: Discussion: Linking Flow Structures and Morphodynamicsmentioning

confidence: 65%

“…However, substantial erosion and deposition of fine sediment occurs in areas that are closely linked to secondary flow structures. For example, Howard and Dolan [1981], Schmidt [1990], Schmidt and Graf [1990], and Rubin et al [1990] described the basic flow structures and morphologic linkages for the Colorado River in Grand Canyon (Figure 1; this reach contains our study sites). Schmidt [1990] described the basic geomorphic unit as the “fan‐eddy complex” because tributary debris fans constrict the main channel and the expansions result in flow separation and zones of lateral recirculation, or eddies (Figure 2).…”

Section: Introductionmentioning

confidence: 99%

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Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

Wright

Kaplinski

2011

J. Geophys. Res.

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[1] In canyon rivers, debris fan constrictions create rapids and downstream pools characterized by secondary flow structures that are closely linked to channel morphology. In this paper we describe detailed measurements of the three-dimensional flow structure and sandbar dynamics of two pools along the Colorado River in the Grand Canyon during a controlled flood release from Glen Canyon Dam. Results indicate that the pools are characterized by large lateral recirculation zones (eddies) resulting from flow separation downstream from the channel constrictions, as well as helical flow structures in the main channel and eddy. The lateral recirculation zones are low-velocity areas conducive to fine sediment deposition, particularly in the vicinity of the separation and reattachment points and are thus the dominant flow structures controlling sandbar dynamics. The helical flow structures also affect morphology but appear secondary in importance to the lateral eddies. During the controlled flood, sandbars in the separation and reattachment zones at both sites tended to build gradually during the rising limb and peak flow. Deposition in shallow water on the sandbars was accompanied by erosion in deeper water along the sandbar slope at the interface with the main channel. Erosion occurred via rapid mass failures as well as by gradual boundary shear stress driven processes. The flow structures and morphologic links at our study sites are similar to those identified in other river environments, in particular sharply curved meanders and channel confluences where the coexistence of lateral recirculation and helical flows has been documented.Citation: Wright, S. A., and M. Kaplinski (2011), Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona,

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Section: Discussion: Linking Flow Structures and Morphodynamicsmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

Wright

Kaplinski

2011

J. Geophys. Res.

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“…Field methods and grain‐size analyses for the 1997 and 1998 samples were previously reported by Topping et al [2000b]. Channel‐margin deposits were not systematically sampled in this study because the average grain‐size was found by Schmidt and Graf [1990] to be similar to that of eddy bars. Because the average differences between the 1997, 1998, and 1999 data were relatively small, we assumed that the mean 1997–1999 grain‐size distributions for the main‐channel and eddy storage environments were good approximations for the grain‐size distributions in these storage environments in other years.…”

Section: Sediment Storage In the Postdam Rivermentioning

confidence: 99%

“…There is strong evidence that fine‐sediment sizes are segregated among depositional environments. Generally, fine sediment on the main‐channel bed is medium and coarse sand with little or no silt or clay [ Wilson , 1986; Schmidt and Graf , 1990; Topping et al , 2000b]. In contrast, the sizes of sediment in eddy bars and channel‐margin deposits are finer [ Howard and Dolan , 1981; Schmidt and Graf , 1990; Budhu and Gobin , 1994; Rubin et al , 1998; Topping et al , 1999; Topping et al , 2000b].…”

Section: Sediment Storage In the Postdam Rivermentioning

confidence: 99%

Influence of a dam on fine‐sediment storage in a canyon river

et al. 2006

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[1] Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the mainchannel bed. We use a combination of methods, including direct measurement of sediment storage change, measurements of sediment flux, and comparison of the grain size of sediment found in different storage sites relative to the supply and that in transport, in order to evaluate the change in both the volume and location of sediment storage. The analysis shows that the bed of the main channel was an important storage environment for fine sediment in the predam era. In years of large seasonal accumulation, approximately 50% of the fine sediment supplied to the reach from upstream sources was stored on the main-channel bed. In contrast, sediment budgets constructed for two short-duration, high experimental releases from Glen Canyon Dam indicate that approximately 90% of the sediment discharge from the reach during each release was derived from eddy storage, rather than from sandy deposits on the main-channel bed. These results indicate that the majority of the fine sediment in Marble Canyon is now stored in eddies, even though they occupy a small percentage ($17%) of the total river area. Because of a 95% reduction in the supply of fine sediment to Marble Canyon, future high releases without significant input of tributary sediment will potentially erode sediment from long-term eddy storage, resulting in continued degradation in Marble Canyon.

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“…Throughout Marble Canyon, debris fans, large rapids, and recirculating eddies are common. Upper Marble Canyon is narrower than lower Marble Canyon and has a lower frequency of eddies and associated sandbars [ Schmidt and Graf , ; Hazel et al ., ]. We refer to these two parts of Marble Canyon as mass‐balance segments.…”

Section: Description Of Study Areamentioning

confidence: 99%

Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: Issues of scale, geomorphic setting, and sampling design

et al. 2013

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[1] Measurements of morphologic change are often used to infer sediment mass balance. Such measurements may, however, result in gross errors when morphologic changes over short reaches are extrapolated to predict changes in sediment mass balance for long river segments. This issue is investigated by examination of morphologic change and sediment influx and efflux for a 100 km segment of the Colorado River in Grand Canyon, Arizona. For each of four monitoring intervals within a 7 year study period, the direction of sandstorage response within short morphologic monitoring reaches was consistent with the flux-based sand mass balance. Both budgeting methods indicate that sand storage was stable or increased during the 7 year period. Extrapolation of the morphologic measurements outside the monitoring reaches does not, however, provide a reasonable estimate of the magnitude of sand-storage change for the 100 km study area. Extrapolation results in large errors, because there is large local variation in site behavior driven by interactions between the flow and local bed topography. During the same flow regime and reach-average sediment supply, some locations accumulate sand while others evacuate sand. The interaction of local hydraulics with local channel geometry exerts more control on local morphodynamic response than sand supply over an encompassing river segment. Changes in the upstream supply of sand modify bed responses but typically do not completely offset the effect of local hydraulics. Thus, accurate sediment budgets for long river segments inferred from reach-scale morphologic measurements must incorporate the effect of local hydraulics in a sampling design or avoid extrapolation altogether.Citation: Grams, P. E., D. J. Topping, J. C. Schmidt, J. E. Hazel Jr., and M. Kaplinski (2013), Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: Issues of scale, geomorphic setting, and sampling design,

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Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

Cited by 94 publications

References 8 publications

Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

Influence of a dam on fine‐sediment storage in a canyon river

Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: Issues of scale, geomorphic setting, and sampling design

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