K.R.G. Reef1, P.C. Roos1, H.M. Schuttelaars2, S.J.M.H. Hulscher1

1 Water Engineering and Management, University of Twente: This email address is being protected from spambots. You need JavaScript enabled to view it.

2 Institute of applied Mathematics, Delft University of Technology.


Barrier coasts are important for coastal safety, ecology, tourism, and economy. They consist of a back-barrier basin connected to a larger sea/ocean through multiple tidal inlets. Using an exploratory model based on Escoffier’s approach (1940), Roos et al. (2013) found equilibrium configurations and reproduced the observed patterns of inlet spacing in mesotidal multiple inlet systems (Stutz and Pilkey 2011). They adopted a strongly schematized geometry of the back-barrier basin: rectangular and of uniform depth. However, this does not reflect the spatial variation in back-barrier basin width that is commonly observed in e.g. the Wadden Sea.


To investigate the effect that a spatial variation in back-barrier basin has on the long-term morphological evolution of barrier coasts, we extend the model of Roos et al. (2013) to allow arbitrary geometries to be included in the model. A first test with a conically shaped basin shows that where the barrier coast is wider, more and larger inlets are present. The opposite holds for the narrower part of the basin. An example model run is shown in Figure .


Escoffier EF (1940) The stability of tidal inlets. Shore and Beach 8:114–115

Roos PC, Schuttelaars HM, Brouwer RL (2013) Observations of barrier island length explained using an exploratory morphodynamic model. Geophys Res Lett 40:4338–4343. doi: 10.1002/grl.50843

Stutz ML, Pilkey OH (2011) Open-ocean barrier islands: Global influence of climatic, oceanographic, and depositional settings. J Coast Res 27:207–222. doi: 10.2112/09-1190.1

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Figure 1: Example run showing the evolution of a barrier coast from a saturated coast with many open inlets (A), evolving over time (B) towards an equilibirum state with 9 open inlets (C).

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