A spectral model for estimating temporal and spatial evolution of rippled seabeds

作者：Nelson Timothy R^*; Voulgaris George

来源：Ocean Dynamics, 2015, 65(2): 155-171.

DOI：10.1007/s10236-014-0801-y

• Time-dependent ripple model
• Spectral model
• Transient ripples
• Relict ripples
• Ripple orientation
• Ripple wavelength
• Ripple height

Existing time variable ripple prediction models have focused on ripple wavelength and height yet have not accounted for the effect of wave directionality on ripple evolution. These models use an equilibrium ripple sub-module that provides the target geometry of the seabed. Temporal variability of the hydrodynamic conditions cause ripple geometry to lag behind and not always agree with that predicted by equilibrium models. In this contribution, previous work is extended through the development of a new 2-D, time variable, spectral ripple model that allows for the estimation of ripple wavelength, height, and orientation. Since ripple irregularity is associated with directionality, the new model also has the ability to predict the irregularity of the rippled seabed. A comparison of the 2-D and existing time-dependent models is carried out using both synthetic and field ripple data that consist of time series representing a variety of wave-forcing conditions. Under strong wave forcing with no orientation changes, the 2-D model predicts ripple wavelength and orientations that agree with those of existing models. During periods of change in wave directions, the 2-D model predicts a significantly smaller ripple height during ripple reorientation. Under weaker energy flows, the 2-D model yields improved estimates especially for relict ripple geometry. In addition, the 2-D model's spectrum yields a prediction of the seabed irregularity.

• 出版日期2015-2