Competing feedback in an idealized tide-influenced delta network

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Niccolò Ragno , Nicoletta Tambroni, Michele Bolla Pittaluga


The morphodynamic evolution of river deltas is intimately tied to flow and sediment partitioning at bifurcations. In this work, we investigate the long-term equilibrium configuration of a simple delta network using an analytical model, which accounts for the effect of small tidal oscillations.
Differently from individual bifurcations, where tidal action is always a stabilizing factor, in the case of a tree-like delta with multiple bifurcations a dual response emerges.
Specifically, depending on the values of four reference parameters function of tidal amplitude, upstream flow conditions, and on the geometry of the channels, tides can either promote or discourage an unbalanced discharge distribution. This behavior primarily concerns the apex bifurcation, which is affected by the variations of the relative tidal amplitude at the internal nodes. In turn these variations depend on how flow and sediment are diverted upstream. Finally, we discuss the outcomes of the model performing a qualitative comparison with field and experimental tide-influenced deltas. Results highlight the need of including in a unified scheme river-influenced (i.e. depositional) and tide-influenced (i.e. erosional) effects.



Earth Sciences, Geomorphology, Physical Sciences and Mathematics


Bifurcations, Tide-influenced deltas, Morphodynamic equilibrium, Feedback


Published: 2021-12-03 05:23

Last Updated: 2021-12-03 10:23


CC BY Attribution 4.0 International

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