Numerical Model Study of Breakwaters at Grand Isle, Louisiana

Gravens, Mark B.; Rosati, Julie Dean

doi:10.21236/ada285332

Cited by 6 publications

(1 citation statement)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Borrow pits were dredged at this site for a beach nourishment project in 1983 and the formation of erosional hot spots on the nourished beach were documented by Combe and Soileau (1987). Gravens and Rosati (1994) found that wave refraction and diffraction induced by the pits influenced the subsequent shoreline response; however, the present results suggest that wave reflection may have also played a significant role in the observed erosion.…”

Section: Borrow Pitscontrasting

confidence: 81%

Wave Reflection from Nearshore Depressions

Michalsen¹,

Haller

Suh

2008

J. Waterway, Port, Coastal, Ocean Eng.

View full text Add to dashboard Cite

This study employs an existing finite-difference model based on the hyperbolic form of the Modified Mild Slope Equation (MMSE) to investigate wave reflection near bathymetric depressions such as dredged borrow pits and nearshore canyons. First, the model is tested for numerical limitations on the higher order bottom slope and curvature terms using a idealized cases of a simple depth transition and a symmetric trapezoidal trench, with comparisons of the MMSE to both the traditional Mild Slope Equation (MSE) solution and a shallow water analytic solution. It is demonstrated that the model gives accurate solutions on slopes as steep as 1:1, and that the solutions from all three models agree in the shallow water region. However, for waves in intermediate depths, predicted wave reflection from nearshore depressions is shown to differ significantly between the MMSE and MSE models. Next, geometrical data from a wide range of existing and proposed borrow pits and a submarine canyon are gathered and analyzed for whether wave reflection is an important process near realistic nearshore depressions. The geometric data show that realistic nearshore depressions lie within the tested range of the MMSE model and that borrow pits are generally not in shallow water, which means it is important to use an MMSE-type model to calculate reflection from these features. In addition, storm conditions on average lead to a 50% increase in reflection coefficient in comparison to the mean wave conditions, due to the increase in wave period. Finally, the results also indicate borrow pit design criteria that can be used to ensure minimal reflection.

show abstract

Section: Borrow Pitscontrasting

confidence: 81%