Comparison of Revetment and Sill in Reducing Shore Erosion and Wave Overtopping

A laboratory experiment was conducted in a wave flume to compare sand beach profile evolution and wave overtopping of a sand berm for the three cases of (1) no structure, (2) a stone revetment protecting the steep sand berm, and (3) a stone sill reducing wave action on the berm. The revetment reduced onshore sand transport on the fronting beach but was effective in protecting the sand berm and reducing wave overtopping. The revetment crest was damaged during major wave overtopping. The sill reduced the beach profile change but was not very effective in reducing wave overtopping and berm erosion when the sill crest was submerged sufficiently. An existing numerical model (CSHORE) was upgraded for its application to the sill test where the emerged sill crest became submerged during the test. The upgraded model was compared with the measured wave transformation, wave overtopping, and overwash rates and beach profile evolution in the three tests consisting of 90 runs with each run lasting 400 s. The model was also used to predict the settlement of the revetment and sill for the case of no filter below the stone structure. The limited experiment and numerical modeling quantified the capability and limitations of the revetment and sill.