Patterns in the sand: From forcing templates to self-organization

Coco, Giovanni; Murray, A. Brad

doi:10.1016/j.geomorph.2007.04.023

Cited by 180 publications

(155 citation statements)

References 92 publications

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“…Thus, younger bedforms tend to be short-crested, shorter in wavelength and irregular in shape, while more mature features are longer in both wavelength and crest length. This merging and lengthening is observed in nature (eg, Clarke and Werner 2004) and in other modeling studies (eg, Coco and Murray 2007, Werner and Kocurek 1999, Jerolmack and Mohrig 2005. Clarke and Werner (2004) observed that the growth of bedforms (wavelengths) from a flat bed to maturity occurred first linearly and then became logarithmic.…”

Section: Figure 3 Profiles Across Simulated Bedforms Along Lines Marsupporting

confidence: 55%

Observations and Predictions of Bedforms in Tidal Inlets and River Mouths

Gallagher

2011

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Gallagher, Edith L. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) Franklin and Marshall CollegeFranklin and Marshall College DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.The long term objective of the proposed study is to model and measure bedforms in tidal inlets and river mouths. We use an existing self-organization model to predict multiple scales of bedforms and we will make measurements of bedforms within combined flow environments (May 2012). The model's predictive skill will then be evaluated. This grant was for 1 year only and included funds to begin model development, to interact with the CSDMS group, and to participate in an ONR program review (June 2010). These activities have all been completed and a follow-on ONR grant has been awarded. PREDICTIONS OF BEDFORMS IN TIDAL INLETS AND RIVER MOUTHS LONG-TERM GOALSThe long-term goals of the study are to model and measure bedforms in tidal inlets and river mouths. Specifically, the goals are: 1) to use an existing self-organization model to predict multiple scales of bedform formation, growth and migration in combined steady, tidal and wave-driven flows, 2) to compare model predictions with measurements (from both the literature and from a tidal inlet/river mouth experiment), 3) to test the hypothesis that subaqueous bedforms will grow indefinitely for a given set of conditions and that different scales of bedforms will occur simultaneously because of this continuous growth, and 4) to incorporate this bedform model into community modeling systems (eg CSDMS) to improve modeling of flow, sediment transport and morphology change in river mouths and tidal inlets. OBJECTIVESThe specific objectives of this study have been to Ø develop and adapt the present model for flows in river mouths and tidal inlets (expand the model to 2-D flows, improve flow drivers, scale the model up for larger spatial domains and begin to examine multiple bedform scales). Ø continue working with the CSDMS so that the present model can be utilized by that community modeling environment. Ø participate in the ONR-supported tidal inlet and river mouth experiment with Tom Lippmann at CCOM/UNH to generate a data set on bedforms in a tidal inlet.

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Section: Figure 3 Profiles Across Simulated Bedforms Along Lines Marsupporting

confidence: 55%

Observations and Predictions of Bedforms in Tidal Inlets and River Mouths

Gallagher

2011

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“…They may also focus, forming a freak wave (Pelinovsky et al, 2010). Sometimes, edge waves are also associated with beach cusp formation (Guza and Imman, 1975;Komar, 1998;Masselink, 1999;Dodd et al, 2008;Coco and Murray, 2007).…”

Section: Introductionmentioning

confidence: 99%

Subharmonic resonant excitation of edge waves by breaking surface waves

Abcha

Zhang

Ezersky

et al. 2017

Nonlin. Processes Geophys.

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Abstract. Parametric excitation of edge waves with a frequency 2 times less than the frequency of surface waves propagating perpendicular to the inclined bottom is investigated in laboratory experiments. The domain of instability on the plane of surface wave parameters (amplitude-frequency) is found. The subcritical instability is observed in the system of parametrically excited edge waves. It is shown that breaking of surface waves initiates turbulent effects and can suppress the parametric generation of edge waves.

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“…Model studies first explained alongshore sandbar variability from a hydrodynamic template in the water motion (Bowen and Inman, 1971;Holman and Bowen, 1982); present-day models rely on the principle of self-organisation (Hino, 1975;Sonu, 1972;Falqués et al, 2000;Coco and Murray, 2007), in which a crescentic sandbar forms spontaneously through the positive feedback between the flow, sediment processes and the evolving morphology. The genesis of crescentic patterns in single sandbar systems is thus reasonably well understood.…”

Section: Introductionmentioning

confidence: 99%

Morphological coupling in multiple sandbar systems – a review

Price

Ruessink

Castelle³

2014

Earth Surf. Dynam.

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Abstract. Subtidal sandbars often exhibit alongshore variable patterns, such as crescentic plan shapes and rip channels. While the initial formation of these patterns is reasonably well understood, the morphodynamic mechanisms underlying their subsequent finite-amplitude behaviour have been examined far less extensively. This behaviour concerns, among other aspects, the coupling of alongshore variable patterns in an inner bar to similar patterns in a more seaward bar, and the destruction of crescentic patterns. This review aims to present the current state of knowledge on the finite-amplitude behaviour of crescentic sandbars, with a focus on morphological coupling in double sandbar systems. In this context we include results from our recent study, based on a combination of remote-sensing observations, numerical modelling and data-model integration. Morphological coupling is an inherent property of double sandbar systems, where the inner bar may attain a type of morphology not found in single bar systems. Coupling is governed by water depth variability along the outer-bar crest and by various wave characteristics, including the offshore wave height and angle of incidence. In recent research, the role of the angle of wave incidence for sandbar morphodynamics has received more attention. Numerical modelling results have demonstrated that the angle of wave incidence is crucial to the flow pattern, sediment transport, and thus the emerging morphology of the coupled inner bar. Moreover, crescentic patterns predominantly vanish under highangle wave conditions, highlighting the role of alongshore currents in straightening sandbars and challenging the traditional conception that crescentic patterns vanish under high-energy, erosive wave conditions only.

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Patterns in the sand: From forcing templates to self-organization

Cited by 180 publications

References 92 publications

Observations and Predictions of Bedforms in Tidal Inlets and River Mouths

Observations and Predictions of Bedforms in Tidal Inlets and River Mouths

Subharmonic resonant excitation of edge waves by breaking surface waves

Morphological coupling in multiple sandbar systems – a review

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