Modelling An Estuary Over Long Time Periods

Due to the special geographic features and high rate of biological productivity of the estuary; analyzing the evolution of an estuary over long time periods is important in understanding and predicting environmental changes in the natural ecosystem. To predict the behavior the varied flow conditions in the natural phenomena, a simpler mathematics model is required to analyze it. Averaging methods are extensively used for fluid studies. Based on the changing flow conditions, the time span could be divided into three periods, long time, medium and short period. In this paper, a long-term averaging model for the estuary is introduced to predict the flow variation, sediment transport and bed morphology change. In addition, various variables which may influence the river system are discussed and some reasonable values of these variables are estimated based on the experience. By introducing the time scales and instantaneous variables into the one- dimensional hydraulic equations of momentum, sediment transport and bed morphology change, three simplified equations are obtained. A case study on the Snowy River is discussed in this paper.