A comparison of overtopping behaviour over a permeable and impermeable crest

A comparison of overtopping behaviour over a permeable and impermeable crest: An insight into overtopping discharges and intensities

Afridi, Z.N.

Verhagen, H.J. (mentor)

Civil Engineering and Geosciences

Hydraulic Engineering

2010-08-03

The purpose of this report is to investigate the differences in overtopping characteristics over the crest of a rubble mound breakwater when the crest is made either impermeable or permeable. Among numerous characteristics that are effected by a modification in the permeability of the crest, this report looks specifically into three separate aspects: the design level changes that are caused by modifications in the permeability of the crest, a comparison of the total and sector-wise overtopping discharges and finally the differences in spatial overtopping intensities between the two. By looking into two well-known overtopping design guidelines for overtopping, namely, Owen and Eurotop, this report aims to look at the differences it would make in designing a breakwater with either an impermeable or a permeable crest. This is done by building a breakwater model in a wave flume and comparing it with the existing guidelines and assessing the changes that best represent the modified model. It is also important to observe how this physical modification of the crest affects the overtopping discharges and spatial overtopping intensities behind the crest of the breakwater. This will be relevant for designers or contractors tasked to make changes to an existing breakwater that results in its crest becoming impermeable. An insight into the overtopping discharges and intensities will be extremely useful to be able to predict the overall changes and cater for them.

overtopping
breakwater
permeability
porosity
waves

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Student theses

student report

(c) 2010 Afridi, Z.N.