Nearshore sandbar rotation at single-barred embayed beaches

25Citations
Citations of this article
38Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

The location of a shore-parallel nearshore sandbar derived from 7 years of video imagery data at the single-barred embayed Tairua Beach (NZ) is investigated to assess the contribution of barline rotation to the overall morphodynamics of sandbars in embayed environments and to characterize the process of rotation in relation to external conditions. Rotation induces cross-shore barline variations at the embayment extremities on the order of magnitude of those induced by alongshore uniform cross-shore migration of the bar. Two semiempirical models have been developed to relate the barline cross-shore migration and rotation to external wave forcing conditions. The rotation model is directly derived from the cross-shore migration model. Therefore, its formulation advocates for a primary role of cross-shore processes in the rotation of sandbars at embayed beaches. The orientation evolves toward an equilibrium angle directly related to the alongshore wave energy gradient due to two different mechanisms. Either the bar extremities migrate in opposite directions with no overall cross-shore bar migration (pivotal rotation) or the rotation relates to an overall migration of the barline which is not uniform along the beach (migration-driven rotation). Migration and rotation characteristic response times are similar, ranging from 10 to 30 days for mild and energetic wave conditions and above 200 days during very calm conditions or when the bar is located far offshore.

Cite

CITATION STYLE

APA

Blossier, B., Bryan, K. R., Daly, C. J., & Winter, C. (2016). Nearshore sandbar rotation at single-barred embayed beaches. Journal of Geophysical Research: Oceans, 121(4), 2286–2313. https://doi.org/10.1002/2015JC011031

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free