How Do Wave Absorbers Work?

Channel geometry and coastal structure material contribute a large portion to wave attenuation. Water waves act similarly to sound waves. When they hit a highly reflective structure, they bounce off with relatively no energy absorbed. Steel sheet pile is a good example of this because it is vertical and non-porous so little if any wave energy is absorbed. By contrast, approximately 40% of a rubblemound structure consists of voids. These voids between the rocks can absorb a significant amount of energy, in turn reducing wave heights. A wave absorber is basically a modified rubblemound structure integrated into an existing steel sheet pile harbor structure. Figure 1 shows a wave before it enters the wave absorber.

Figure 1 - Waves before entering wave absorber

Figure 2 shows the same wave moments later. This wave has now traveled past the wave absorber. It is easy to see just how much energy can be absorbed. Both of these photos were taken at Pentwate, Michigan.

Figure 2 - Wave after leaving wave absorber

The following animation (figure 3) shows a computer model of Pentwater Harbor. As it can be seen in the computer model, wave absorbers have been effective in reducing wave energy.

Figure 3 - Pentwater Harbor wave absorber animation