Littoral Hydrodynamics and Sediment Transport Around a Semi- Permeable Breakwater

The increased rate of shoaling in Dana Point Harbor requires a better understanding of hydrodynamics and sediment transport around a permeable breakwater. In this study, an integrated coastal wave, hydrodynamic and sediment transport numerical model was developed to investigate the circulation and sedimentation patterns around the harbor, to address sediment seepage through the permeable West Breakwater, and to assist find solutions to reducing the shoaling inside the harbor. The model calibration and validation were conducted against field measurements of waves, current, and water surface elevation, and a laboratory experiment of low-crested structures (LCS). Comparisons of the calculated results and the measurements indicate that waves are the dominant forcing outside the harbor. Inside the harbor, currents are wind- and tide-driven with small current magnitude of less than 4 cm/sec. The distribution of morphology change shows significant sediment movement and sediment pathways around the West Breakwater. The calculated annual sediment rate in the inner side of the breakwater was comparable to the sediment accumulation rate available from historical dredging records.