The process of shoreline changes due to transport of sediment by littoral drift is studied in this paper. Pelnard-Consid`ere is the commonly adopted model. This model is based on the principle of sediment conservation, without diffraction. In this research, we adopt the Pelnard-Consid`ere equation with diffraction, and a numerical scheme based on the finite volume method is implemented. Shoreline development in a groyne system is then simulated. For a case study, the Sanur Bali Beach, Indonesia is considered, in which from Google Earth photos, the beach experiences changes of coastline caused by sediment trapped in a groyne system.