The Sensitivity of Tidal Channel Systems to Initial Bed Conditions, Vegetation, and Tidal Asymmetry

In tidal environments, channel networks act as essential drainage pathways. Although the complex interactions between environmental factors have been studied extensively, the effects of the initial bathymetry on tidal network ontogeny are poorly understood. In this contribution, we used a numerical model to mimic a schematic tidal basin subjected to tidal forcing. The effects of the initial bathymetry and vegetation growth are analyzed by changing the features of randomly generated bed perturbation and the intertidal platform slope. Different perturbation densities mildly affect the growth of tidal networks, which, at equilibrium, share similar values in terms of channel length, tidal prism, and cross-sectional area. The complexity and structure of channel networks are more sensitive to variations in the perturbation distribution. Increasing the initial bathymetry slope can shorten channels and reduce the tidal prism and drainage efficiency. Vegetation growth is found to invariably promote channel lengthening and narrowing, increasing the complexity and drainage efficiency of the system. An asymmetrical tidal forcing generally leads to longer channels and smaller unchanneled lengths. Under ebb-dominant conditions, channels get deeper, and the increased channel length ensures a higher drainage efficiency. The insights of our study provide a deeper understanding of the environmental factors controlling the equilibrium morphology of tidal channel systems and their overall resilience. Further implications concern the restoration and management of coastal areas through the informed use of topographic changes and planting arrangements. Finally, accounting for the uncertainties associated with initial conditions is relevant when modeling other earth systems and comparing them with real systems.

Automated summary

In this study, a numerical model was used to investigate the effects of initial bathymetry on the ontogeny of tidal networks in a tidal basin. It was found that different perturbation densities have mild effects on the growth of tidal networks, while changes in perturbation distribution significantly affect the complexity and structure of the channel networks. Vegetation growth was found to increase channel length and narrowness, leading to higher complexity and drainage efficiency of the system.