First Results of a Long Term Morphodynamic Process Based Model

Long-term morphological and basin filling modelling studies traditionally comprehend simulations carried out by conceptual, geometric, behaviour-oriented or, more recently, dynamic abstracted diffusion models. The increase or computational capability and the development of new mathematical approaches, allowed the use of more complex models. This will enable, in the near future, a shift from the synthesis to the reductionist paradigm. In this new approach, numerical algorithms are used to solve explicitly the physical equations of the relevant processes, coupled with empirical and semi-empirical equations for the unresolved phenomena, that will create the possibility of working with a wide range of time and space scales. In this work, the first results of a long-term morphodynamic evolution obtained with a process based model are presented. The used model is the MOHID modelling system, which simulates explicitly the hydrodynamic, sand transport and the bottom's dynamics. For that purpose a schematic bathymetry was constructed representing a coastal zone with 50 km in length and I km in width. The model considers a tidal input at open boundary, while the freshwater input is neglected. The results of 2000 years simulations were compared with other approaches of morphodynamic's modelling. The use of a process based model requires a considerable computational effort, so in order to reduce that, an extrapolation scheme is proposed and tested against standard runs. The results obtained show a decrease in the computational load to one third, maintaining the data consistency.