Non-Linear Morphodynamic Response Of Deltas To Extreme Events
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https://doi.org/10.1029/2025GL120954 <-- shared paper
“ABSTRACT: Deltas, the interface between riverine and coastal systems, host ∼500 million people and function as crucial ecological nexuses. The magnitude and frequency of extreme floods are projected to intensify as climate changes, yet the potential impacts on delta morphodynamics remain poorly understood. Using the pyDeltaRCM numerical model, [they] explore[d] the impact of extreme flow frequency on delta morphology. Morphometric analyses demonstrate a non-linear morphodynamic response across two orders of magnitude of extreme flow intermittencies, I. Under medium I, deltas are smallest with the fewest, narrowest channels. In contrast, at both low and high I, deltas grow the largest, with the widest and most numerous channels. Channel mobility appears unaffected and delta slope declines monotonically as I increases. [They] identif[ied] drivers of this non-linear response, generating a novel conceptual model of delta adjustment to extreme flows. [Their] morphodynamic projections can help anticipate and manage geomorphic change on deltas undergoing flood-frequency change.
PLAIN LANGUAGE SUMMARY: River deltas, at the interface between rivers and coasts, host ∼500 million people and vital ecological habitats. In rivers, flood magnitude and frequency are expected to change in future, but we don’t yet know how these changes will affect the shape or behavior of the deltas where these rivers meet the coast. [They] use[d] a set of simplified digital river models to simulate how deltas in different climate zones (e.g., temperate or polar) might change as river flood frequency increases. Our model suggests that river deltas respond non-linearly to flood frequency. At either low or high flood frequency, [their] simulated deltas grew extensively and developed wide channels. On the other hand, at medium flood frequency, deltas were smaller with narrower channels, and floods caused the most erosion when they occurred with medium frequency. This non-linear response highlights the unexpected ways in which river deltas might adjust their behavior and form as climate change shifts river flood frequency in the future…”
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