Understanding differences between DELFT3D and empirical predictions of alongshore sediment transport gradients

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Abstract

Predictions of alongshore transport gradients are critical for forecasting shoreline change. At the previous ICCE conference, it was demonstrated that alongshore transport gradients predicted by the empirical CERC equation can differ substantially from predictions made by the hydrodynamics-based model Delft3D in the case of a simulated borrow pit on the shoreface. Here we use the Delft3D momentum balance to examine the reason for this difference. Alongshore advective flow accelerations in our Delft3D simulation are mainly driven by pressure gradients resulting from alongshore variations in wave height and setup, and Delft3D transport gradients are controlled by these flow accelerations. The CERC equation does not take this process into account, and for this reason a second empirical transport term is sometimes added when alongshore gradients in wave height are thought to be significant. However, our test case indicates that this second term does not properly predict alongshore transport gradients.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Understanding differences between DELFT3D and empirical predictions of alongshore sediment transport gradients
DOI 10.1142/9789814277426_0154
Year Published 2009
Language English
Publisher World Scientific
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 12 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Proceedings of the 31st International Conference, Coastal Engineering 2008
First page 1864
Last page 1875