Bedforms and their hydraulic stability relationships in a tidal environment, Bay of Fundy, Canada

Dalrymple, Robert W.; Knight, R D; Lambiase, Joseph J.

doi:10.1038/275100a0

Cited by 228 publications

(148 citation statements)

References 11 publications

Supporting

Mentioning

135

Contrasting

Unclassified

Order By: Relevance

“…3). Similarly, Dalrymple et al (1978) observed that in the Bay of Fundy the largest bedforms occur in sand coarser than 0.3 mm. However, in the flume data collected by Guy et al (1966), and in a plot of flume data by Znamenskaya (1966), maximum sand-wave height does not appear to increase with sediment size.…”

Section: Sand-wave Heightmentioning

confidence: 94%

“…In some cases, superimposed bedforms develop in response to temporal flow changes (Allen, 1978), In other cases, however, two or more scales of bedforms exist in equilibrium with a single steady flow (Guy et al, 1966;Harms et al, 1974;Boothroyd and Hubbard, 1975;Dalrymple et al, 1978). Small bedforms superimposed on larger ones are not merely a curiosity.…”

Section: Equilibrium Superimposed Bed Formsmentioning

confidence: 99%

“…Some sedimentologists have subdivided the group of large-scale bedforms that form in 0.3--0.5 mm sand into various classes of megaripples, dunes, and sand waves on the basis of size (Coleman, 1969;Boothroyd and Hubbard, 1975), morphology (Znamenskaya, 1963;Allen, 1968;Hine, 1975;Southard, 1975), or both (Dalrymple et al, 1978). These authors have demonstrated that as the flow over a bed increases in velocity or decreases in depth, the crests of large-scale bedforms become sinuous in plan view, and scour pits develop in bedform troughs (in Allen's terminology the bedforms become three-dimensional).…”

Section: Bed Form Terminologymentioning

confidence: 99%

“…Rubin and McCulloch (1976) extended bed-phase boundaries to depths of many tens of meters by observing bedforms and flow conditions in deep (up to 85 m) tidal flows in San Francisco Bay. Dalrymple et al (1978) determined bed-phase bound, aries for intermediate flow depths (3--14 m) in Bay of Fundy, Canada. The purposes of the present paper are: (1) to present observations of bedforms generated by tidal flows in central San Francisco Bay; (2) to combine those observations with shallow-flow observations to determine the relations between flow conditions, bed phase, and sand-wave height for a wide range of depths; (3) to relate bed phase to shear velocity; and (4) to relate superimposed bedforms and their distribution to vertical and lateral variations in shear velocity in flows over large bedforms.…”

Section: Purposementioning

confidence: 99%

“…In Fig. 8, the San Francisco Bay bed-phase observations were combined with those of Southard (1975), Boothroyd and Hubbard (1975), and Dalrymple et al (1978), and a single set of bed-phase boundaries was drawn from the combined data. The figure shows that within limited grain-size ranges: (1) as depth increases, each bed phase occurs at increasing velocities, and (2) that increasing the velocity produces the same sequence of bed phases as decreasing the depth.…”

Section: Bed Phasementioning

confidence: 99%

See 4 more Smart Citations

Single and superimposed bedforms: a synthesis of San Francisco Bay and flume observations

Rubin

McCulloch

1980

Sedimentary Geology

224

128

View full text Add to dashboard Cite

Section: Sand-wave Heightmentioning

confidence: 94%

Section: Equilibrium Superimposed Bed Formsmentioning

confidence: 99%

Section: Bed Form Terminologymentioning

confidence: 99%

Section: Purposementioning

confidence: 99%

Section: Bed Phasementioning

confidence: 99%

See 3 more Smart Citations

Single and superimposed bedforms: a synthesis of San Francisco Bay and flume observations

Rubin

McCulloch

1980

Sedimentary Geology

224

128

View full text Add to dashboard Cite

Three‐dimensional versus two‐dimensional bed form‐induced hyporheic exchange

Chen

Cardenas

Chen

2015

Water Resources Research

View full text Add to dashboard Cite

The hyporheic zone is often a critical component of river systems. Hyporheic exchange is generally forced by variation in riverbed topography such as due to bed forms. Most previous research on bed form-driven hyporheic flow has focused on two-dimensional (2-D) dunes and ripples, while little has been done on their three-dimensional (3-D) counterparts. Here we compared hyporheic exchange and associated metrics for a previously studied pair of corresponding 2-D and 3-D bed forms. To accomplish this, a series of multiphysics computational fluid dynamics models were conducted both in 2-D and 3-D with similar open channel Reynolds numbers (Re). Results show that the pressure gradient along the sediment-water interface is highly sensitive to the spatial structure of bed forms, which consequently determines hyporheic flow dynamics. Hyporheic flux is a function of Re for both 2-D and 3-D dunes via a power law; however, the equivalent 3-D dunes have a higher flux since the 3-D form induces more drag. The hyporheic zone depths and volumes are only slightly different with the 3-D case having a larger volume. The mean fluid residence times for both cases are related to Re by an inverse power law relationship, with the 3-D dune having smaller residence times at moderate to high Re. The effects of increasing flux on residence time in 3-D dunes are partly modulated by a slightly increasing hyporheic volume. Our results suggest that a 2-D idealization is a reasonable approximation for the more complex 3-D situation if local details are unimportant but that development of predictive models for mean fluxes and residence times, which are critical for biogeochemical processes, based on 2-D models may be insufficient.

show abstract

Numerical modeling of subaqueous sand dune morphodynamics

et al. 2016

View full text Add to dashboard Cite

The morphodynamic evolution of subaqueous sand dunes is investigated, using a 2‐D Reynolds‐averaged Navier‐Stokes numerical model. A laboratory experiment where dunes are generated under stationary unidirectional flow conditions is used as a reference case. The model reproduces the evolution of the erodible bed until a state of equilibrium is reached. In particular, the simulation exhibits the different stages of the bed evolution, e.g., the incipient ripple generation, the nonlinear bed form growing phase, and the dune field equilibrium phase. The results show good agreement in terms of dune geometrical dimensions and time to equilibrium. After the emergence of the first ripple field, the bed growth is driven by cascading merging sequences between bed forms of different heights. A sequence extracted from the simulation shows how the downstream bed form is first eroded before merging with the upstream bed form. Superimposed bed forms emerge on the dune stoss sides during the simulation. An analysis of the results shows that they emerge downstream of a slight deflection on the dune profile. The deflection arises due to a modification of the sediment flux gradient consecutive to a reduction in the turbulence relaxation length while the upstream bed form height decreases. As they migrate, superimposed bed forms grow on the dune stoss side and eventually provoke the degeneration of the dune crest. Cascading merging sequences and superimposed bed forms dynamics both influence the dune field evolution and size and therefore play a fundamental role in the dune field self‐organization process.

show abstract

Bedforms and their hydraulic stability relationships in a tidal environment, Bay of Fundy, Canada

Cited by 228 publications

References 11 publications

Single and superimposed bedforms: a synthesis of San Francisco Bay and flume observations

Single and superimposed bedforms: a synthesis of San Francisco Bay and flume observations

Three‐dimensional versus two‐dimensional bed form‐induced hyporheic exchange

Numerical modeling of subaqueous sand dune morphodynamics

Contact Info

Product

Resources

About