Sediment Entrainment Potential in Modified Alluvial Streams: Implications for Re-Mobilization of Stored In-Channel Sediment

Davis, Lisa

doi:10.2747/0272-3646.30.3.249

Cited by 9 publications

(4 citation statements)

References 29 publications

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“…Ratios of actual hydraulic values in each section to critical values for the range of sizes found were calculated (Fig. 6) 35,59 .…”

Section: Methodsmentioning

confidence: 99%

Extreme sediment fluxes in a dryland flash flood

Hooke

2019

Sci Rep

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A flash flood on 28th September, 2012, rose to a peak discharge of 2357 m3 s−1 from zero within one hour in the ephemeral Nogalte channel in SE Spain. Channel morphology and sediment sizes were measured at existing monitored sites before and after the flood and peak flow hydraulics calculated from surveyed floodmarks and cross-sections. Maximum peak sediment fluxes were calculated as ~600 kg s−1 m−1, exceeding maximum published, measured dryland channel values by 10 times and common perennial stream fluxes by 100 times. These high fluxes fit the established simple bedload flux - shear stress relations for dryland channels very well, but now extended over a much wider data range. The high sediment fluxes are corroborated by deposits at >1 m height in a channel-side tank, with 90 mm diameter sediment carried in suspension, by transport of large blocks and by massive net aggradation as extensive, structureless channel bars. Very high sediment supply and rapid hydrograph rise and recession produced the conditions for these exceptional sediment dynamics. The results demonstrate the extreme sediment loads that may occur in dryland flash floods and have major implications for catchment and channel management.

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“…Ratios of actual hydraulic values in each section to critical values for the range of sizes found were calculated (Fig. 6) 35,59 .…”

Section: Methodsmentioning

confidence: 99%

Extreme sediment fluxes in a dryland flash flood

Hooke

2019

Sci Rep

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“…Another example where streams do not follow the classic CEM progression is seen in small tributaries in the Southeast USA. Davis (, ) found that homogenous bank materials promote simultaneous widening and incision as the primary form of adjustment within the same watershed. Rhoads and Urban () and Urban and Rhoads () revealed that channelization did not produce significant bed‐level changes along the Embarras River, Illinois, which they attributed to low stream power and resistant bed materials.…”

Section: An Overview Of Classic Channel Evolution Modelsmentioning

confidence: 99%

Channels in the Making – An Appraisal of Channel Evolution Models

Dyke

2013

Geography Compass

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Over the past 30 years, fluvial geomorphologists have sought to understand the historical trajectory of channel adjustments after disturbance by developing channel evolution models (CEMs). These models use a combination of quantitative data and qualitative indicators to describe the spatial progression of channel evolution. This article surveys the historical development of CEMs, how they function, and what types of CEMs are best suited for different geomorphic settings. It describes the logic underlying classic CEMs, and their subsequent application to predict channel response following dam removal. After this, it recounts the emergence of multi-pathway CEMs, which have been used to capture the evolutionary trajectories in complex fluvial systems (e.g., anastomosing rivers). Lastly, it argues that a state-and-transition framework offers an appropriate modeling template to document channel evolution in a wide variety of fluvial systems, including those originally modeled using classic CEMs. A state-and-transition approach sees rivers as composed of interrelated process and form (morphological) states. They identify under what conditions a river channel would undergo a transition from one formal state to another (e.g., from a single-threaded to braided planform). They can also be used to understand the form-process dynamics underlying subtle morphological transitions that produce changes in a river's biogeomorphological structure without triggering wholesale river metamorphosis.

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“…Alluvial bench occurrence has been related to sediment transport-limited conditions (Changxing et al, 1999;Schumm, 2005), the maintenance of stream equilibrium-accreting during drought-dominated periods to contract the channel and eroding during flood-dominated periods to widen the channel (Erskine and Livingstone, 1999), sediment dynamics associated with specific flow stages (mean annual Q or bankfull Q, for example) (Osterkamp and Hupp, 1984), or localized hydraulic changes that initiate deposition (Vietz et al, 2011). While not often the focus of many geomorphic studies in the past, benches have been documented in regions varying from subarctic (Hickin, 1979) to arid (Marren et al, 2006) and in a variety of geologic settings (Webb et al, 2002;Davis, 2009). Benches serve as finescale ecotones bridging aquatic and riparian zones, provide habitat for many species, and can be highly effective carbon and nitrogen sinks (Powell and Bouchard, 2010).…”

Section: Introductionmentioning

confidence: 97%