Bedform movement recorded by sequential single-beam surveys in tidal rivers

Dinehart, R.L.

doi:10.1016/s0022-1694(01)00558-3

Cited by 49 publications

(33 citation statements)

References 18 publications

(19 reference statements)

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“…

\bar{C_{bf}} = \underset{t > t_{normale}}{false\sum} C_{normalbf}

C bf ( t ) was recorded by tracking the displacement of bedform crests ∆ x = x 2 − x 1 over the time interval ∆ t = t 2 − t 1 (e.g. Coleman, ; Dinehart, ; Claude et al ., ).…”

Section: Experimental Set‐up and Methodologymentioning

confidence: 99%

A unified model for bedform development and equilibrium under unidirectional, oscillatory and combined‐flows

et al. 2014

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The development of bedforms under unidirectional, oscillatory and combined-flows results from temporal changes in sediment transport, flow and morphological response. In such flows, the bedform characteristics (for example, height, wavelength and shape) change over time, from their initiation to equilibrium with the imposed conditions, even if the flow conditions remain unchanged. These variations in bedform morphology during development are reflected in the sedimentary structures preserved in the rock record. Hence, understanding the time and morphological development in which bedforms evolve to an equilibrium stage is critical for informed reconstruction of the ancient sedimentary record. This article presents results from a laboratory flume study on bedform development and equilibrium development time conducted under purely unidirectional, purely oscillatory and combined-flow conditions, which aimed to test and extend an empirical model developed in past work solely for unidirectional ripples. The present results yield a unified model for bedform development and equilibrium under unidirectional, oscillatory and combined-flows. The experimental results show that the processes of bedform genesis and growth are common to all types of flows, and can be characterized into four stages: (i) incipient bedforms; (ii) growing bedforms; (iii) stabilizing bedforms; and (iv) fully developed bedforms. Furthermore, the development path of bedform; growth exhibits the same general trend for different flow types (for example, unidirectional, oscillatory and combined-flows), bedform size (for example, small versus large ripples), bedform shape (for example, symmetrical or rounded), bedform planform geometry (for example, two-dimensional versus three-dimensional), flow velocities and sediment grain sizes. The equilibrium time for a wide range of bed configurations was determined and found to be inversely proportional to the sediment transport flux occurring for that flow condition.

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“…

\bar{C_{bf}} = \underset{t > t_{normale}}{false\sum} C_{normalbf}

C bf ( t ) was recorded by tracking the displacement of bedform crests ∆ x = x 2 − x 1 over the time interval ∆ t = t 2 − t 1 (e.g. Coleman, ; Dinehart, ; Claude et al ., ).…”

Section: Experimental Set‐up and Methodologymentioning

confidence: 99%

A unified model for bedform development and equilibrium under unidirectional, oscillatory and combined‐flows

et al. 2014

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show abstract

“…Sediment in channels that convey relatively large flows, such as the Sacramento River, San Joaquin River, and Threemile Slough, tend to be sandy and contain bed forms (Dinehart 2002 Larger river floods that winnow fines from the bed and larger sand supply in the Sacramento River probably account for the difference between the two rivers. At Rio Vista, Thompson and others (2000) observed that large floods increased the percent of sand on the bed (up to nearly 100% from nearly 0%), and benthic assemblages shifted from species that favor muddy sediment to sandy sediment.…”

Section: Delta Sediment Propertiesmentioning

confidence: 99%

“…This bed load was only 1.4% of the total sediment load. From 1998 to 2000, Dinehart (2002) collected several pairs of bedform measurements about one week apart to estimate bedload transport rates of 15 to 73 metric tons per day at Garcia Bend downstream from Sacramento. Wright and Schoellhamer (2005) report that the daily suspended-sediment load at Freeport, about 6 kilometers downstream from Garcia Bend, averaged about 3,000 metric tons per day during water years 1999 to 2002.…”

Section: Suspended and Bed Loadmentioning

confidence: 99%

Conceptual Model of Sedimentation in the Sacramento–San Joaquin Delta

Schoellhamer¹,

Wright²,

Drexler³

2012

SFEWS

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Sedimentation in the Sacramento-San Joaquin River Delta builds the Delta landscape, creates benthic and pelagic habitat, and transports sediment-associated contaminants. Here we present a conceptual model of sedimentation that includes submodels for river supply from the watershed to the Delta, regional transport within the Delta and seaward exchange, and local sedimentation in open water and marsh habitats. The model demonstrates feedback loops that affect the Delta ecosystem. Submerged and emergent marsh vegetation act as ecosystem engineers that can create a positive feedback loop by decreasing suspended sediment, increasing water column light, which in turn enables more vegetation. Sea-level rise in open water is partially countered by a negative feedback loop that increases deposition if there is a net decrease in hydrodynamic energy. Manipulation of regional sediment transport is probably the most feasible method to control suspended sediment and thus turbidity. The conceptual model is used to identify information gaps that need to be filled to develop an accurate sediment transport model.

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“…Porterfield (1980) estimated that bedload transport (or, more accurately, unmeasured transport; see reference for details) accounted for 13% of the total transport at the Sacramento gage (11447500) for the time period 1957-1966, using the daily suspended-sediment discharge data and modified Einstein procedure (Colby and Hembree 1955). Also, Dinehart (2002) investigated bedform transport mechanics near the Freeport gage using bedform-mapping techniques. Bedload transport rates (or, more accurately, bedform transport; see reference for details) for several time periods between July 1998 and April 2000, including a period of high flow in January 2000, were only 1% to 2% of the total transport.…”

Section: Flow and Sediment Data Recordsmentioning

confidence: 99%