Processes of long-term coastal evolution and their mathematical modelling: Application to the Mozambican coast

Different processes in response to the action of natural driven forces and the human interference on coastal systems act together, contributing to shape the coast. Coastal evolution models have been developed as useful tools to better understand the contribution of different processes on observed coastal changes, and also to anticipate future evolution in response to different actions and interventions taking place along the coast.

The predominant practice in coastal modelling is to have models that address separately the evolution as a result of cross-shore sediment transport processes from the ones caused by processes with main effects on the alongshore sediment transport. However, if longer time and spatial scales are to be covered by such models, a combination of cross-shore and longshore processes is crucial. In this context, the thesis explores the possibility of improving the mathematical modelling of long-term coastal evolution by integrating cross-shore evolution processes into a regional coastal evolution model.

The developed models were satisfactorily tested against available data, as they could reproduce the observed coastal evolution. The model development stage was followed by its application to simulate the long-term coastal evolution of selected coastal stretches of Mozambique’s 2800-km-long coastline. Based on a literature review of different processes influencing the evolution of the Mozambican coast, the potential contribution of mathematical models to improve the local coastal planning and management was explored.

With the model application to the Mozambican coast, it was possible to estimate sediment transport rates, and to reproduce the long-term evolution of the coast, for a period up to nearly two decades. For that reason, mathematical models are considered a valid tool to improve the understanding of the historical long-term
coastal evolution, and to anticipate how it will change in the future. The latter information would be valuable for the improvement of the protection of coastal sensitive systems, reinforcing the integration component, the use of soft approaches in coastal protection projects, and for the definition of setback lines.