Intertidal eco-geomorphological dynamics and hydrodynamic circulation

The overall dynamics of intertidal environments are governed by complex interactions between their ecological and geomorphological components. A more comprehensive understanding of such dynamics and their predictive modelling can only be achieved through the description of the feedbacks coupling hydrodynamics and sediment transport, on one hand, and ecological processes on the other. Toward the goal of a comprehensive theoretical framework describing the large-scale, long-term evolution of the intertidal landscape, we describe an eco-morphodynamic model which allows the investigation of the long-term evolution of tidal networks, the adjacent marsh platforms, and the vegetation colonizing them. On the basis of observational indications regarding the different time scales governing the various landscape-forming processes, the model decouples the initial rapid network incision from its subsequent slower elaboration (chiefly by meandering) and from the eco-morphological evolution of intertidal platforms. The planimetric development of tidal channel networks coupled to the vertical accretion of the adjacent marsh platform, explicitly accounting for the vegetation distribution, and the consequence of marine transgressions and regressions, are modelled and analyzed. The resulting eco-morphodynamic model reproduces the hydrodynamic and sedimentation patterns typical of intertidal environments and is used to explore the response of tidal eco-geomorphologies to different scenarios of changing sea-level, incoming sediment concentrations and halophytic vegetation characteristics. Complex network structures and tidal patterns meeting distinctive statistical properties of actual network structures and showing several observed characteristics of ecological and geomorphic relevance are reproduced by the model.