The Coupling of Numerical Flow and Sediment Transport Models - a Case Study

Numerical unsteady flow models have been used for many years to assist in prediction of river flooding and tidal flow. More recently, several sediment transport models have been developed for examining and quantifying sediment movement under both flood arid tidal events. This paper briefly describes the various types of numerical unsteady flow and sediment transport models in use, and specific areas of application. A major study of flooding and sediment movement in the Barron River Delta, near Cairns in North Queensland, is presented as a case study, where a specific type of unsteady flow numerical model, and a specific sediment model are coupled together to provide a useful tool in analysing existing flooding, as well as the effects of various proposed developments within the delta. The unsteady flow model used is a link-node type, quasi-two-dimensional model, with over 200 channels and 100 nodes to represent the delta. Sediment movement considered is predominantly that of non-cohesive materials. The advantages of this method of coupling numerical flow and sediment transport models over the more generally adopted fixed bed approach, particularly for streams with large sediment loads, are discussed. Finally, potential weaknesses of the method of coupling numerical flood and sediment transport models are discussed.