DYNAMICS OF LONGSHORE BARS

Magnus Larson, NIcholas C. Kraus

Abstract


This paper presents empirical predictive expressions describing the cross-shore movement of linear nearshore bars, based on intensive analysis of survey data from Duck, North Carolina. The analysis centers on 300 beach profile surveys taken at approximately 2-week intervals for the continuous period from 1981 to 1989, together with accurate measurements of the wave conditions. The geometry and dynamics of bars derived from the surveys are related to wave characteristics, and criteria previously developed by the authors to predict beach erosion and accretion are found to be applicable to bar movement if a multiplicative empirical coefficient in each criterion is modified. The results indicate that onshore movement of bars is more probable than previously estimated. The implication is that linear bars formed of dredged material are more likely to move onshore to nourish the surf zone and beach than previously thought.

Keywords


longshore bar; bar dynamics

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