@article{8733005,
  abstract     = {{The existence of morphodynamic equilibria of double-inlet systems is investigated using a cross-sectionally averaged morphodynamic model. The number of possible equilibria and their stability strongly depend on the forcing conditions and geometry considered. This is illustrated by considering a rectangular double-inlet system forced by M-2 tidal constituents only. Depending on the M-2 amplitudes and phases at both entrances, no equilibrium, one equilibrium or multiple morphodynamic equilibria may exist. In case no equilibrium is found, the minimum water depth becomes zero somewhere in the system, reducing the double-inlet system to two single-inlet systems. In the other cases, the location of the minimum water depth and the direction of the tidally-averaged sediment transport, as well as their actual values, depend strongly on the M-2 tidal characteristics. Such parameter sensitivity is also observed when including the residual and M-4 forcing contributions to the water motion, and when allowing for width variations. This suggests that, when considering a specific system, the number and stability of morphodynamic equilibria, as well as the characteristics of these quantities, can only be assessed by investigating that specific system in detail. As an example, the Marsdiep-Vlie inlet system in the Dutch Wadden Sea is considered. It is found that, by using parameter values and a geometry characteristic for this system, the water motion and bathymetry in morphodynamic equilibrium are qualitatively reproduced. Also the direction and order of magnitude of the tidally-averaged suspended sediment transport compare well with those obtained from a high-complexity numerical model.

Plain Language Summary An idealized model is developed to systematically investigate the cross-sectionally averaged morphodynamic equilibria in double-inlet systems with varying width. A bathymetric profile is in equilibrium with the water motion and sediment transport, if there is no accumulation of tidally averaged sediment transport, associated with the equilibrium bed. Considering a constant-width system, the number of morphodynamic equilibria strongly depends on the tidal forcings. For an M2 tidal forcing only, it is found that no equilibrium, one equilibrium or more than one morphodynamic equilibria can exist. The location and the depth of the watershed, and the total sediment transport are used to characterize the morphodynamic equilibria. Typically, the watershed tends to get closer to the inlet with a larger tidal amplitude, and the total transport is directed from the inlet with the largest tidal amplitude to the one with the smallest tidal amplitude. Taking parameter values representative of the Marsdiep-Vlie system, one stable morphodynamic equilibrium is found. Inclusion of the large-scale width variations observed in the Marsdiep-Vlie system is essential to obtain an equilibrium profile that qualitatively reproduces the observed width-averaged bathymetry, water motion and tidally-averaged sediment transport.

Key Points

A cross-sectionally averaged morphodynamic model has been developed to assess equilibria of double-inlet systems at tidal barrier coasts

No equilibrium, one equilibrium or multiple stable equilibria may exist, depending on the forcing conditions

For a good comparison with the Marsdiep-Vlie system, inclusion of the basin's width variation is essential}},
  articleno    = {{e2021JF006266}},
  author       = {{Deng, X. and Meerman, C. and Boelens, Thomas and De Mulder, Tom and Salles, P. and Schuttelaars, H. M.}},
  issn         = {{2169-9003}},
  journal      = {{JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE}},
  keywords     = {{Earth-Surface Processes,Geophysics,double inlet systems,tidal basins,process-based models,morphodynamic equilibria,bifurcations,BARRIER ISLANDS,TIDAL INLETS,MODEL,CIRCULATION,EVOLUTION,SEDIMENT,BASINS,SEA}},
  language     = {{eng}},
  number       = {{12}},
  pages        = {{23}},
  title        = {{Morphodynamic equilibria in double‐inlet systems : existence and stability}},
  url          = {{http://doi.org/10.1029/2021jf006266}},
  volume       = {{126}},
  year         = {{2021}},
}

Altmetric

View in Altmetric

Web of Science

Times cited: