Permeable breakwaters


Research is being carried out on the following: permeable sections in rubble mound breakwaters, new types of permeable breakwater, aeration of the enclosed basin, and use of pontoon breakwaters. Permeable sections are favorably positioned inside the breakwater, in regard to the distinctive natural flow generators (wind action and wind waves), which enables efficient seawater exchange in enclosed basins without investing additional energy on the seawater pumping. The permeable sections are equipped with floodgates, which prevents wave energy transmission in stormy wave events. The research group also develops new types of permeable breakwaters which could be applied in locations with milder climates. In ports with exceptionally poor circulation, it is possible to aerate the seawater and force circulation with pumps in periods of great pollution concentrations (e.g. harmful algal blooms). It is our goal to define standard measures for achieving optimal seawater quality for smaller and simpler ports.

Experiment design

Figure 1. Types of permeable breakwater configuration

Objectives and goals

The use of permeable breakwaters with submerged vertical panels enables the circulation of the seawater beneath the breakwater, but the vertical panels should be also immersed deep enough to prevent excessive wave energy transmission. Upon the occurrence of large significant wave height waves, in conjunction with the transmission of the wave energy underneath the breakwater, there could also be wave energy transmission due to overtopping. The breakwater designers should take both into consideration when calculating the breakwater functionality. These types of breakwaters are applied to locations with a weak wind wave climate (fetch sizes of less than 10-20 km) due to the threat of significant wave energy transmission, which could prevent regular operations inside the marina or harbour basin. This type of permeable breakwater can be applied on the entire length of the breakwater or only as a smaller part that would allow greater seawater exchange.


Phase I (2017):

Laboratory studies are currently being conducted in the hydraulic laboratory of the Faculty of Civil Engineering, University of Zagreb. The research focuses on the irregular wave transmission underneath the vertical panel of the permeable breakwater.

Experiment design

Figure 1. Laboratory experiment design

Video 1. Laboratory experiments of wave energy transmission through permeable breakwater