Breakwaters under construction exposed to oblique waves

To investigate this influence of the stone grading on both the two-dimensional deformation and longshore transport new physical model tests were carried out in the wave basin at Delft University of Technology. In total 12 tests were executed in which two different gradings, three different angles of wave attack and two different wave spectra were tested. Data collected from the tests included wave and profile measurements together with the displacements of stones, originating from two colour beams which were applied in the middle of the trunk. These data along with visual observations eventually led to a conceptual model describing stone movements in both transverse and longshore direction. Using Matlab three-dimensional profile and erosion models were generated from which the different profile parameters were determined. With respect to the distance from origin, for each test an exponential relation was derived to describe the stone displacements. After determination of the area of uniform transport these exponential relations were used to calculate the total longshore transport by means of extrapolation and multiple integrations.