From MarineSpecies Introduced Traits Wiki
a groyne is normally a straight structure perpendicular to the shoreline. Groynes work by blocking (part of) the littoral drift, whereby they trap/maintain sand on their upstream side. Groynes can have special shapes and they can be emerged, sloping or submerged, they can be single or in groups, the so-called groyne fields. Groynes are normally built as rubble mound structures, but they can also be constructed in other materials, such as concrete units, timber, etc.
- Groynes as shore protection
- Deteriorated groynes
- For further reading: Mangor, K., Drønen, N. K., Kaergaard, K.H. and Kristensen, N.E. 2017. Shoreline management guidelines. DHI https://www.dhigroup.com/marine-water/ebook-shoreline-management-guidelines.
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