The paper describes the concept of a network model for the morphological behaviour of a near-resonant multiple-inlet tidal basin, as part of a model system which includes the barrier island coasts and the outer deltas. It addresses the question whether a small interference somewhere in such a basin can have major effects on sediment transport and morphology elsewhere in the system. In order to explain the basic ideas of the model, only the main tidal constituent (M2) and the associated topography-induced residual current are considered, not the overtides. Furthermore, the model concerns only non-cohesive sediment (sand). In spite of these simplifications, the model concept is shown to be effective, in that it results in a morphological evolution equation for each branch of the network and a picture of the influence of each branch on the resonance-sensitivity of the system as a whole.