On the initiation of nearshore morphological rhythmicity

Conference paper (2011)

Authors

M.A. de Schipper Hydraulic Structures and Flood Risk - CEG
Roshanka Ranasinghe IHE Delft Institute for Water Education, Hydraulic Structures and Flood Risk - CEG
A.J.H.M. Reniers Rosenstiel School of Marine and Atmospheric Science
M.J.F. Stive Hydraulic Structures and Flood Risk - CEG
Research Group
Hydraulic Structures and Flood Risk (CEG) (TU Delft)
Wave groups Nearshore sandbars Rhythmicity
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Published Date

2011

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Hydraulic Engineering

Research Group

Hydraulic Structures and Flood Risk

Abstract

Nearshore rhythmicity is often initiated in the period just after a storm where the subtidal bar is turned alongshore uniform. The initiation time as well as the length scales of the created rhythmicity varies from one storm period to another. Here we show that the post-storm wave conditions are related to the initiation of the morphological rhythmicity. Narrow-banded and long wave period, both proxies for swell waves, are often found to be present prior to the initiation of rhythmicity. Furthermore, numerical model computations illustrate that swell waves induce significantly larger wave group induced velocities on the bar. These findings imply that the arrival of swell waves can initiate and stimulate the nearshore morphological rhythmicity.