• William Allsop
  • Tom Bruce
  • Adrian Pearson


In the past, many coastal towns or villages constructed harbours for trade and/or fishing. These were protected by breakwaters, commonly rubble mounds to low-water, surmounted by vertical walls of dressed stone blocks (later concrete) with rubble core. Now, 100-150 years later, many such harbours have little or no income to maintain or repair their breakwaters, but meantime, the areas protected have been adopted for commercial and residential purposes, at increased risk of flooding if the 'orphan' breakwater were to collapse, Hampshire et al. (2013). Even after collapse, some wave reduction will however still be afforded by the relict structure. Tests by Allsop et al (2017) have modelled the collapse of several simplified breakwaters, and measured levels of wave transmission over the collapsed structures. This paper extends that work with more analysis of collapsed crest levels, and hence of likely wave transmission.


Allsop, Pearson, & Bruce (2017) Orphan breakwaters - what protection might be given when they collapse? ICE Breakwaters conference. Liverpool.

CIRIA; CUR; CETMEF (2007) The Rock Manual. The use of rock in hydraulic engineering, C683, CIRIA, London. Hampshire, Turner, Hancock & Guthrie (2013) In a Heugh - the strategic influence of a breakwater, Proc ICE Breakwaters Conference, ICE Publishing, ISBN 978-0-7277-5975-7, pp188-198.

How to Cite
Allsop, W., Bruce, T., & Pearson, A. (2018). ORPHAN BREAKWATERS: COLLAPSE AND TRANSMISSION REDUCTION. Coastal Engineering Proceedings, 1(36), structures.53. https://doi.org/10.9753/icce.v36.structures.53