A large scale hydrodynamic model and a regional coastal morphological model have been used to explore the relationship between coastal erosion in north Norfolk and seabed lowering due to dredging off Great Yarmouth. A scenario of extreme dredging was defined and used to modify the boundary conditions of the hydrodynamic model to reveal the sensitivity of nearshore waves. The modified waves were then used to drive the morphological model to predict the coastal erosion. The resulting shorelines were compared to predictions previously made with undredged bathymetry. No significant difference was found in the nearshore wave climate or the shoreline erosion due to the dredging scenario.