NUMERICAL MODEL OF SHORELINE EVOLUTION - SAN DIEGO COUNTY, CA

Client: U.S. Army Corps of Engineers, Los Angeles District

Since Oceanside Harbor was constructed in the 1940s, the downdrift beaches have experienced chronic erosion. To quantify the impacts of the harbor structures and evaluate the effectiveness of candidate mitigation strategies, the U.S. Army Corps of Engineers' Los Angeles District engaged Coastal Frontiers to develop and implement a numerical simulation of long-term coastal change.

The model domain encompasses a 14-mile stretch of the coast in north San Diego County between the Santa Margarita River outlet and Agua Hedionda Lagoon. In the first phase of the project, a Monte Carlo simulation of wave and water level conditions was used to hindcast shoreline evolution with and without the harbor present during the 64-year period from 1934 to 1998. In the second phase, the model was used to forecast future shoreline evolution under scenarios that included no mitigative action, periodic beach nourishment, groin construction, nearshore reef construction, and combinations of nourishment and structural stabilization.

Model Results

Key Model Attributes

  • Calibrated and verified using measured beach change during the 64-year hindcast period from 1934 to 1998

  • Flexible input parameters that include time-varying rates of beach nourishment, phased installation of sediment control structures, and varying rates of sea level rise

  • Comprehensive suite of output parameters that include shoreline change, wave overtopping, revetment damage, bore propagation over the backshore, and forces on backshore structures