Bar response to tides under regular waves

The morphological time scale for the response of outer bar crest level to tidal water-level changes is found to be remarkably short, namely around 15 min for near-prototype wave heights and depths and regular waves. This corresponds to the bar crest level range being 0.77 times the tidal range with a time-lag of only 15 min. Only one near-prototype scale experiment with tide and sufficient time resolution is known to the writers, namely Kraus & Larson (1988) Case 911, which had h(max) = 4.4 m, d(50) = 0.4 mm, a semidiurnal tide range of ca 1 m and regular waves with H = 1.34 m, T = 7.9 s. However, the fast crest-level response is also seen in profile development studies without tide, i.e., the bar crest level generally gets close to its final value in an hour or so while the overall profile adjustment (e.g. seaward bar migration) continues for tens of hours. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.