hollow block revetment
Permeable revetment structures have been used the first time in 1992 at a breakwater structure near the habour entrance of Baltrum Island / North Sea.
Sponsorship: Niedersächsisches Ministerium für Wirtschaft, Technologie und Verkehr, represented by Niedersächsisches Hafenamt Norden, Germany.
Approval: Since 1992 apprpoximately 70 storm tides (water level >= MHW +1.5m) without any damages.

Revetment structure consisting of partly closed hollow bodies through which water can flow parallel to the slope face. Such a structure is capable to influence "wave - structure" interaction extraordinarily.

Modell investigations of scale 1:5 executed at the Fluid Dynamics Laboratory of Bielefeld University of Applied Sciences have shown the following advantageous results compared to those of a quasi smooth (plane) revetment:
hollow block revetment, cross-section

  • Breaker energy reduced by some 40%
  • Energy of washing action reduced by some 50%
  • Collapsing instead of plunging breaker resulting in the probability of wave impacts being almost none
  • Considerable air entrainment improves water quality
  • Porosity of 48% provides protective space for small animals.