|Realistic prediction of beach nourishment performance|
Chul-Hee, Y. (1993). Realistic prediction of beach nourishment performance. PhD Thesis. University of Florida: FL. XIV, 150 pp.
University of Florida, more
Beach nourishment; Coefficients; Erosion; Littoral zone; Models; Numerical analysis; Prediction; Sea surface; Sediment transport; Shoals; Wave refraction; Marine
A simple method is developed for representing wave refraction and shoaling in the vicinity of a beach nourishment project. The method applies for the case of a one-line model of shoreline evolution in which the active profile is displaced seaward or landward without change of form. The model can include the presence of shoreperpendicular structures and background erosion.
The simple method is compared to a one-line model which includes a more detailed grid-based refraction and shoaling algorithm. For all cases tested, the simple method of representing refraction and shoaling results in shoreline evolution in good correspondence with the detailed method. The models are used to illustrate the effects of several features of beach nourishment projects that are of engineering interest.
For purposes of comparison of the model performance with actual data, a nourishment project at Redington Shores, Florida, was monitored to investigate longshore sediment transport processes. Monitoring was carried out over a two-year period and included seven surveys of twenty-six profiles, wave measurements and sediment sampling. These data were analyzed to evaluate three longshore sediment transport formulae and to determine the best-fit coefficients and relative goodness-of-fit.
Beach nourishment, placed along a seawalled shoreline, can exhibit a markedly different behavior than projects on shorelines with adequate compatible sands to transport. The most striking effects of engineering significance are: (1) the migration of the centroid of the nourishment planform anomaly when acted upon by oblique waves, and (2) a potentially different rate of spreading of the planform anomaly. Under the most idealized consideration, the speed of centroid migration is shown to increase as the planform anomaly spreads out under the mobilizing action of the waves and the rate at which the planform spreading (dispersion) occurs is not affected by the seawall. Also, for normal incident waves, the seawall does not affect the planform evolution. Analtyical, numerical and experimental approaches are employed to demonstrate the aforementioned effects.