A Mathematical Model to Predict Frequency of Sand Nourishment in Straight Beaches

Beach nourishment is a viable engineering solution for shore protection by stabilizing beaches. However, beach nourishment may not be technically or economically feasible or justified for some sites, particularly those with high erosion rates. The frequency of re-nourishment is one of the important parameters that could be used to justify beach nourishment process for a given shoreline. Mathematical models could be effectively used for the above purpose. A mathematical model was developed for the simulation of shoreline changes due to both the longshore and crossshore sediment transport and there by, frequency of re-nourishment could be estimated. This model is an improved version to the typical'one-line model'. The model has been calibrated and verified against the field data collected from a beach nourishment project implemented in 2003 in a coastal stretch leading from Maha Oya to Lansigama in the west coast of Sri Lanka. The model results proved that the model is capable of simulating shoreline changes with a reasonable accuracy. Median grain size of beach sand and depth of closure are more sensitive to the model predictions compared to other input parameters. The applicability of the model is limited to straight coastlines without the presence of structures.