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Beach variability near groynes

More:  Institute 
Acronym: BVANG
Period: April 2005 till April 2008
Status: Completed

Institute  Top 

Abstract:
"The topic of the proposed research is the investigation of the variability of beaches close to beach control structures. Beaches change their shape (or morphology) in response to the prevailing environmental conditions - a combination of waves, currents, water levels and wind. To the casual observer this can suggest benign fluctuations about some typical or mean shape. However, extremes of variation about the mean, both positive and negative, can have serious repercussions. Engineered structures such as groynes, artificial headlands and detached breakwaters are used as means to control the movement of sediment on the beach. Despite such measures, beach levels can vary substantially in response to changes in the prevailing wave conditions; and such variations are often most significant close to the structures. Large positive variations correspond to a full beach and, where groynes are present can signify that the groynes are no longer being effective at controlling longshore sediment transport. Under oblique wave attack sediment will accumulate on the updrift side of a groyne and erode on the down drift side. This can cause large changes in beach level across the groyne and adversely affect the safety and amenity of the beach. Large negative variations correspond to beach erosion. Where this occurs it can reduce the effectiveness of the structures and, in extremis, lead to structural damage.
Our aim is to develop a stochastic approach to shoreline modelling that will allow both the average and the variance of the shoreline near beach structures to be determined directly. A secondary goal is to use the new methods to investigate the impact of changes in wave climate on beach evolution.

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