An idealised study for the long term evolution of crescentic bars. (1st January 2018)

• Record Type: Journal Article
• Authors: Chen, W.L.; Dodd, N.; Tiessen, M.C.H.; Calvete, D.
• Is Part Of: Continental shelf research. Volume 152(2018)
• Page Start: 87
• Page End: 97
• Publication Date: 2018-01-01
• Subjects: Crescentic bed-patterns -- Linear stability analysis -- Field observations -- Long term evolution -- Nearshore morphology -- Higher harmonic interaction; Continental shelf -- Periodicals; Submarine geology -- Periodicals; 551.41
• DOI: 10.1016/j.csr.2017.11.006
• Languages: English
• ISSNs: 0278-4343

Abstract

Abstract: An idealised study that identifies the mechanisms in the long term evolution of crescentic bar systems in nature is presented. Growth to finite amplitude (i.e., equilibration, sometimes referred to as saturation) and higher harmonic interaction are hypothesised to be the leading nonlinear effects in long-term evolution of these systems. These nonlinear effects are added to a linear stability model and used to predict crescentic bar development along a beach in Duck, North Carolina (USA) over a 2-month period. The equilibration prolongs the development of bed patterns, thus allowing the long term evolution. Higher harmonic interaction enables the amplitude to be transferred from longer to shorter lengthscales, which leads to the dominance of shorter lengthscales in latter post-storm stages, as observed at Duck. The comparison with observations indicates the importance of higher harmonic interaction in the development of nearshore crescentic bar systems in nature. Additionally, it is concluded that these nonlinear effects should be included in models simulating the development of different bed patterns, and that this points a way forward for long-term morphodynamical modelling in general. Highlights: The mechanisms in the long term evolution of crescentic bar systems are identified. Equilibration and higher harmonic interaction are the hypothesised leading nonlinear effects. An idealised model including these effects is developed to predict bar evolution. The comparison with observation emphazises the effect of higher harmonic interaction. These effects should be included in the long term simulation of bed patterns.