The Influence of Wave Nonlinearity on Cross-Shore Sediment Transport in Coastal Zone: Experimental Investigations

Yana Saprykina

doi:10.3390/app10124087

Abstract

On the basis of field experiment data, the main features of influence of non-linear wave transformation scenarios on cross-shore sediment transport in coastal zones were investigated. The bottom deformations due to the non-linear wave transformation follow the specific scenario. The increase in the second non-linear harmonic amplitude leads to the erosion of the underwater slope at the distances corresponding to this process, with the subsequent accumulation of sandy material closer to the shore at distances where the amplitude decreases during the backward energy transfer to the first harmonic. This can be explained by the change in the phase shift between harmonics during non-linear wave transformation. The second harmonic maximum provides the point near which the bottom deformations occur in different directions. Scenarios of non-linear wave transformation in which backward energy transfer from the second non-linear harmonic to the first is close to the shoreline will contribute to the transport and accumulation of the sediment on the coast. These scenarios are more characteristic of “small waves”. The scenario without a periodical exchange of wave energy between non-linear harmonics (with an increase in the second harmonic only) that is characteristic of large storm waves and plunging breaking waves will lead to the erosion of the underwater bottom profile.

Highlights

Waves play an important role in coastal zone morphodynamic; in particular, they influence on erosive and accumulative processes of the sand deposits
On the basis of field data, it has been shown that the underwater bottom relief deformations during the non-linear wave transformations and wave energy exchange between first and second non-linear wave harmonics follow a specific scenario
The maximum of the second harmonic amplitude is the point near which the bottom relief deforms in different directions

Summary

Introduction

Waves play an important role in coastal zone morphodynamic; in particular, they influence on erosive and accumulative processes of the sand deposits. Due to non-linear wave transformation, the sediments can move in the cross-shore direction and affect the underwater bottom profile shape. This is due to the asymmetry of near-bed orbital velocities, which is connected with wave asymmetry (for example, [5,6,7]). There are many commonly used formulae to predict sediment transport resulting from near-bed orbital velocity asymmetry under non-linear Stokes-type waves [8,9,10,11,12,13,14].

Objectives

Findings

Discussion

Conclusion