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Evaluation of Morphodynamic Controls on the Preservation of Fluvial Meander-belt Deposits
  • Na Yan,
  • Luca Colombera,
  • Nigel P Mountney
Na Yan
University of Leeds

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Luca Colombera
University of Leeds
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Nigel P Mountney
University of Leeds
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Abstract

The way river morphodynamics influence the preservation of point-bar deposits at different spatio-temporal scales is hitherto unquantified. Employing time-lapse trajectories of natural rivers, a numerical model is used here to simulate planform evolutions of meander-belt reaches that embody different transformation behaviors and cutoff processes. Proxies for temporal durations are obtained considering the surface area over which a river migrated and channel migration rates that relate to average channel radius of curvature through constant, monotonic and non-monotonic relationships. The preservation of meander-belt deposits over different timescales is assessed at three architectural hierarchies: (i) pairs and (ii) sets of accretion packages, and (iii) meander-belts. Results show that sediment preservation decreases in a predictable way with the accumulation time; however, accretion rates decay with time in a way that does not follow the expected power-law. This is interpreted to reflect the effect of the onset of geomorphic thresholds of channel transformation and cutoff.
28 Aug 2021Published in Geophysical Research Letters volume 48 issue 16. 10.1029/2021GL094622