15 Mar 2023
 | 15 Mar 2023

Statistical characterization of erosion and sediment transport mechanics in shallow tidal environments. Part 1: erosion dynamics

Andrea D'Alpaos, Davide Tognin, Laura Tommasini, Luigi D'Alpaos, Andrea Rinaldo, and Luca Carniello

Abstract. Wave-induced bottom shear stress is one of the leading processes that control sediment erosion dynamics in shallow tidal environments, because it is responsible for sediment resuspension and, jointly with tidal currents, for sediment reworking on tidal flats. Reliable descriptions of erosion events are foundational to effective frameworks relevant to the fate of tidal landscape evolution. However, the absence of long-term, measured time series of bottom shear stress (BSS) prevents a direct analysis of erosion dynamics. Here we adopted a fully-coupled, bi-dimensional numerical model to compute BSS generated by both tidal currents and wind waves in six historical configurations of the Venice Lagoon in the last four centuries. The one-year-long time series of the total BSS were analyzed based on the peak-over-threshold theory to statistically characterize events that exceed a given erosion threshold and investigate the effects of morphological modifications on spatial and temporal erosion patterns. Our analysis suggests that erosion events can be modeled as a marked Poisson process in the intertidal flats for all the considered configurations of the Venice Lagoon, because interarrival times, durations and intensities of the over-threshold exceedances are well described by exponentially distributed random variables. Moreover, while the intensity and duration of over-threshold events are temporally correlated, almost no correlation exists between them and interarrival times. The resulting statistical characterization allows for a straightforward computation of morphological indicators, such as erosion work, and paves the way to a novel synthetic, yet reliable, approach for long-term morphodynamic modeling of tidal environments.

Andrea D'Alpaos et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-319', Anonymous Referee #1, 13 Apr 2023
    • AC1: 'Reply on RC1', Davide Tognin, 02 Jun 2023
  • RC2: 'Comment on egusphere-2023-319', Anonymous Referee #2, 23 Apr 2023
    • AC2: 'Reply on RC2', Davide Tognin, 02 Jun 2023

Andrea D'Alpaos et al.

Data sets

Statistical characterization of erosion mechanics in shallow tidal environments Davide Tognin, Andrea D'Alpaos, and Luca Carniello

Andrea D'Alpaos et al.


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Latest update: 26 Sep 2023
Short summary
Sediment erosion induced by wind waves is one of the main drivers of the morphological evolution of shallow tidal environments. However, a reliable description of erosion events for the long-term morphodynamic modelling of tidal systems is still lacking. By statistically characterizing sediment erosion dynamics in the Venice Lagoon over the last four centuries, we set up a novel framework for a synthetic, yet reliable, description of erosion events in tidal systems.