A simple model of bedform migration

Bartholdy, Jesper; Ernstsen, Verner Brandbyge; Flemming, Burghard W.; Bartholomä, Alexander

doi:10.1002/esp.2002

Cited by 6 publications

(18 citation statements)

References 31 publications

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“…Durán et al (2010) provide a review of continuous 'minimal' models, which attempt to capture the dynamics of dunes with limited parameterizations, together with new simulations using a similar model to describe the formation and evolution of barchan dunes. Bartholdy et al (2010) highlight a different approach to modeling bedform scale processes and dune migration. The model is used to examine barchan development from an initial sand pile, and demonstrates good agreement with field data.…”

Section: Introductionmentioning

confidence: 99%

Bedforms: views and new perspectives from the third international workshop on Marine and River Dune Dynamics (MARID3)

Parsons

Best

2013

Earth Surf Processes Landf

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This Commentary introduces a Special Issue of Earth Surface Processes and Landforms dedicated to the memory of Stephen Coleman (1966–2012) who sadly passed away on July 23, 2012. Stephen was an incredible enthusiast for the study of bedforms and made seminal contributions to our knowledge and understanding of flow, sediment transport and bedform dynamics. Stephen presented a keynote address at MARID 3, which has led to this Special Issue (see Coleman SE, Nikora VI. 2011. Fluvial dunes: initiation, characterization, flow structure. Earth Surface Processes and Landforms 36: 39–57. DOI. 10.1002/esp.2096) and was always keen to discuss research, from theory to techniques to experiments. He was always generous with his time and touched many with the influence of his thoughts and intellect. Our community has lost an outstanding scientist and Stephen will be greatly missed by us all. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

Bedforms: views and new perspectives from the third international workshop on Marine and River Dune Dynamics (MARID3)

Parsons

Best

2013

Earth Surf Processes Landf

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“…

u_{*, c r i t}

is the critical bed‐shear velocity, estimated from the critical Shields parameter, which was taken to be 0.04 from Bartholdy et al . [] for a grain size of 0.7 mm.

η_{v}

was calculated where observations of velocity were available.…”

Section: Discussionmentioning

confidence: 99%

“…Lin and Venditti [] propose a power law relation for bed form translation,

V = a {true(θ / θ_{c r i t} true)}^{m} \times B C F

, where a is the regression intercept, θ is the Shields parameter, θ crit is the critical Shields parameter, taken to be 0.04 for a grain size of 0.7 mm [ Bartholdy et al ., ], and m is the regression slope. BCF is the bias correction factor.…”

Section: Discussionmentioning

confidence: 99%

“…Three equations were selected from the literature to represent a range of approaches for estimating sediment flux to compare with (7). The first equation [ Bartholdy et al ., ] relates sediment flux over the crest of subaqueous dunes, q B , to the excess shear stress acting on the dune crest in terms of friction velocity at the crest,

u_{* c}

q_{B} = β D θ_{c} true(u_{* c} - u_{* c r i t} true),

where β = 27 is a dimensionless constant calibrated with observations of sediment flux in a small, straight laboratory flume [ Guy et al ., ], D is the average grain size,

θ_{c} = u_{* c}^{2} / true(s_{s} - 1 true) g D

, and

u_{* c r i t}

is 0.033, the critical friction velocity from the Bartholdy et al . [] fit to the Shields curve.…”

Section: Discussionmentioning

confidence: 99%

“…Since shear stress at the dune crest is rarely measured, Bartholdy et al . [] estimate

u_{*}

from velocity higher in the water column assuming a logarithmic profile [e.g., Yalin , ],

u_{*} = u_{z} / true[8.5 + 2.5 \ln true(z / k_{s} true) true],

where u z is the magnitude of the water velocity,

u_{z} = \sqrt{u_{s}^{2} + u_{n}^{2}}

, at elevation z above the stream bed and the overall hydraulic roughness is

k_{s} = k_{f o r m} + k_{s k i n} .

k form = 0.57 η is the form drag, and

k_{s k i n} = 2.5 D

is skin friction roughness. u z was estimated at the water surface from PIV.…”

Section: Discussionmentioning

confidence: 99%

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Video observations of bed form morphodynamics in a meander bend

2015

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A new optical remote sensing technique for estimating water depth from an oblique camera view is described. The water surface and the bed were imaged simultaneously to create time-dependent maps of the water surface velocities and the bed elevations that can be used to validate numerical models at high spatial and temporal resolution. The technique was applied in a sandy meander bend at the University of Minnesota Saint Anthony Falls Laboratory Outdoor StreamLab. The root mean square differences between optical estimates of the bed and in situ observations ranged between 0.01 and 0.03 m. Mean bed form wavelength was 0.73 m and mean crest height was 0.07 m, but both varied with distance around the meander bend. Bed form classification varied with distance downstream, and sinuosity of bed forms varied with local radius of curvature. Bed form roughness scaled similarly to other natural riverine environments although wavelength and height magnitude and variability were larger than predicted by empirical formulations for straight reaches. Bed form translation rate varied between 1 and 5 mm s 21 . Estimates of velocity from particle image velocimetry (PIV) on the water surface were $10% higher than in situ observations collected $0.05 m below the water surface. Using the PIV observations to drive simple equations for bed load sediment flux, we explained up to 72% of the observed variance in downstream sediment flux. The new methodology described here provides nonintrusive, high spatial and temporal resolution measurements of both the bed and the flow.

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