DETERMINISTIC PROFILE MODELING OF NEARSHORE PROCESSES .2. SEDIMENT TRANSPORT AND BEACH PROFILE DEVELOPMENT

This is the second of two companion papers concerned with the modelling of sediment transport and beach profile response to wave and tidal action. Part I was concerned with the wave and current modelling aspects, whilst the present paper considers the sediment transport and profile development predictions. Particular adaptations of well known theoretical developments that distinguish the present modelling work are described. Both cross-shore and alongshore sediment transport processes (the latter including the influence of tides) are represented. The alongshore transport description is included to allow this quasi-2DV model to act as a module to a quasi-3DH morphodynamic model (the Q3DH model is not described here). The beach profile evolution phase of the model is capable of considering a fixed boundary such as a seawall. The fixed boundary may also be erodible as in the case of a sandy beach overlying a cohesive till substratum. In both Parts I and II, the validity of each individual predictive phase of the model has been assessed. Where the accuracy was found to be insufficient, additional processes were considered until the level of accuracy could be considered suitable for input to the next predictive phase of the model. Whilst free variables exist within the formulation of the model, these have been considered to be fixed in almost every application of the model. The consideration of additional processes is the approach used to achieve improved model prediction, not the arbitrary tuning of free variables. Some of the validation tests for the sediment transport phases (alongshore and cross-shore) are presented in this paper along with evaluations of the integrated model for profile change. The foremost value of the model rests with the ability to identify links between observed beach changes and the underlying coastal processes.