Large-Scale Coastal Morphodynamics: a Simplified Mathematical Model Demonstrating the Possibility of Chaotic Behaviour

A simplified discrete-time mathematical model, demonstrating the possibility of in-trinsically chaotic morphodynamic behaviour of coastal zones with strongly pro-nounced seasonality is presented. The dynamic state of the considered zone is char-acterized by mean concentration of the sediment transported. Assuming a temporarily constant wave climate and using some physical argu-ments based upon known approximate interdependencies between the variations of sediment concentration, grain size, mean bed slope, and the wave-caused morphody-namic effects, a non-linear (logistic-type) evolution relation with only one parameter is obtained. The influence of this parameter on the behaviour of the dynamic system con-sidered is examined by means of numerical calculations. In particular, a parameter interval corresponding to some kind of chaotic behaviour has been found.