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

Schmidt, J.; Graf, Julia B.

doi:10.3133/ofr87555

Cited by 26 publications

(41 citation statements)

References 4 publications

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“…Eddy bars have been studied extensively in Grand Canyon where flow separation is generated at expansions downstream of tributary debris fans (e.g. Howard & Dolan, 1981; Rubin et al ., 1990; Schmidt, 1990; Schmidt & Graf, 1990; Schmidt et al ., 1993; Schmidt & Rubin, 1995; Cenderelli & Cluer, 1998). Pool‐fills are compared with these well‐studied, partly analogous deposits, as discussed below.…”

Section: Channel Forms In Bedrock‐confined Riversmentioning

confidence: 99%

“…These convex‐up deposits, which drape the underlying pool‐fills, are probably akin to the separation bars found capping debris‐fan deposits in Grand Canyon (Rubin et al ., 1990; Schmidt, 1990). Schmidt & Graf's (1990) observation that large Grand Canyon floods tended to erode reattachment bars more extensively than separation bars between 1965 and 1987 suggests that sedimentary units positioned close to the separation point might possess higher preservation potential. If so, this is consistent with the substantial storage terms represented by pool‐fills underlying benches in Sandy Creek.…”

Section: Comparing Pool‐fills With Eddy Bars and Slackwater Depositsmentioning

confidence: 99%

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Pool‐fills: a window to palaeoflood history and response in bedrock‐confined rivers

Jansen

Brierley

2004

Sedimentology

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Channel-scale sedimentary units associated with bedrock-controlled rifflepool morphology are examined in detail along Sandy Creek gorge, an ephemeral stream in arid south-eastern central Australia. Pool-fills comprise cut-and-fill assemblages of poorly sorted sediments ranging in texture from muds to boulders. Five unit types are defined based on particle size, sedimentary structures, geometry and bounding surface character: (1) coarsegrained bar platform; (2) fine-grained bar supraplatform; (3) fine-grained poolfill; (4) fine-grained bench; and (5) modern pool-fill. The last coarse-grained unit currently lining the pools suggests an altered sedimentation style over the post-settlement period (post-ad 1860s). Situated at bedrock valley constrictions, pool-fills are compared with other sedimentary units associated with recirculating currents: eddy bars and slackwater deposits. But only the fine-grained bench units reflect eddy recirculation; the pool-fills are principally forced-bars associated with bedrock-controlled or 'forced' rifflepool morphology. A late Holocene palaeoflood history is proposed based on radiocarbon ages from the pool-fills: multiple phases of cut-and-fill activity were preceded by a superflood 3400-1900 years ago that eroded the pool-fills to bedrock. The resilience of the pool-fills was illustrated by the passage of a 1-in-100-year flood in 1992, which caused only minor erosion. The presence of pool-fills may provide a window to past phases of river activity that cannot be extracted from either historical records/observations or palaeoflood slackwater sediment analyses. The formation and sedimentary preservation potential of these landforms reflect a combination of hydraulic and structural influences, but the occurrence of high-magnitude floods exerts the dominant control.

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Section: Channel Forms In Bedrock‐confined Riversmentioning

confidence: 99%

Section: Comparing Pool‐fills With Eddy Bars and Slackwater Depositsmentioning

confidence: 99%

Pool‐fills: a window to palaeoflood history and response in bedrock‐confined rivers

Jansen

Brierley

2004

Sedimentology

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“…Application of modeling results to assess main stem transport responses to changes in discharge or sand supply requires a characterization of reach‐averaged hydraulic geometry. Schmidt and Graf [1990] used bedrock type near water level as a guide in dividing the channel into geomorphically similar reaches: RM‐15 (the location of Glen Canyon Dam) to RM 0 (Lees Ferry), then bounded at RM 11, 25, 42, 66, 77, and 87. Melis [1997] used debris fan characteristics to determine similar geomorphic reaches that had similar boundaries.…”

Section: Model Componentsmentioning

confidence: 99%

“…Melis [1997] used debris fan characteristics to determine similar geomorphic reaches that had similar boundaries. We used the boundaries of Schmidt and Graf [1990] with one exception. We combined two reaches between river miles 42 and 77 into one reach because they were hydraulically similar.…”

Section: Model Componentsmentioning

confidence: 99%

“…This has resulted in progressive loss of sand storage [ Schmidt et al , 2004]. In the postdam environment, eddies associated with debris fans have been observed to be significant sand deposition sites [ Howard and Dolan , 1981; Schmidt , 1987, 1990; Webb et al , 1989; Rubin et al , 1990; Schmidt and Graf , 1990; Schmidt and Rubin , 1995]. Hazel et al [2006] have demonstrated they are the primary sand storage locations since the closure of Glen Canyon Dam.…”

Section: Introductionmentioning

confidence: 99%

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Reach‐averaged sediment routing model of a canyon river

Wiele

Wilcock

Grams

2007

Water Resources Research

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[1] Spatial complexity in channel geometry indicates that accurate prediction of sediment transport requires modeling in at least two dimensions. However, a one-dimensional model may be the only practical or possible alternative, especially for longer river reaches of practical concern in river management or landscape modeling. We have developed a one-dimensional model of the Colorado River through upper Grand Canyon that addresses this problem by reach averaging the channel properties and predicting changes in sand storage using separate source and sink functions coupled to the sand routing model. The model incorporates results from the application of a two-dimensional model of flow, sand transport, and bed evolution, and a new algorithm for setting the near-bed sand boundary condition for sand transported over an exposed bouldery bed. Model predictions were compared to measurements of sand discharge during intermittent tributary inputs and varying discharges controlled by dam releases. The model predictions generally agree well with the timing and magnitude of measured sand discharges but tend to overpredict sand discharge during the early stages of a high release designed to redistribute sand to higher-elevation deposits.Citation: Wiele, S. M., P. R. Wilcock, and P. E. Grams (2007), Reach-averaged sediment routing model of a canyon river,

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Riparian vegetation, Colorado River, and climate: Five decades of spatiotemporal dynamics in the Grand Canyon with river regulation

et al. 2015

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Documentation of the interacting effects of river regulation and climate on riparian vegetation has typically been limited to small segments of rivers or focused on individual plant species. We examine spatiotemporal variability in riparian vegetation for the Colorado River in Grand Canyon relative to river regulation and climate, over the five decades since completion of the upstream Glen Canyon Dam in 1963. Long-term changes along this highly modified, large segment of the river provide insights for management of similar riparian ecosystems around the world. We analyze vegetation extent based on maps and imagery from eight dates between 1965 and 2009, coupled with the instantaneous hydrograph for the entire period. Analysis confirms a net increase in vegetated area since completion of the dam. Magnitude and timing of such vegetation changes are river stage-dependent. Vegetation expansion is coincident with inundation frequency changes and is unlikely to occur for time periods when inundation frequency exceeds approximately 5%. Vegetation expansion at lower zones of the riparian area is greater during the periods with lower peak and higher base flows, while vegetation at higher zones couples with precipitation patterns and decreases during drought. Short pulses of high flow, such as the controlled floods of the Colorado River in 1996, 2004, and 2008, do not keep vegetation from expanding onto bare sand habitat. Management intended to promote resilience of riparian vegetation must contend with communities that are sensitive to the interacting effects of altered flood regimes and water availability from river and precipitation.

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

Cited by 26 publications

References 4 publications

Pool‐fills: a window to palaeoflood history and response in bedrock‐confined rivers

Pool‐fills: a window to palaeoflood history and response in bedrock‐confined rivers

Reach‐averaged sediment routing model of a canyon river

Riparian vegetation, Colorado River, and climate: Five decades of spatiotemporal dynamics in the Grand Canyon with river regulation

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