Author(s): Y. Y. Jia; J. B. Hinwood
Linked Author(s):
Keywords: Time averaging; Attractors; Estuary; Time-scaled equations
Abstract: To analyse the evolution of an estuary over long time periods, a mathematical model is derived. Averaging methods are used to describe all critical processes in an estuary at three time scales: long time scales (morphological changes), mid period time scales (tidal or flood duration) and short period time scales (turbulence). By introducing the time scales into the one-dimensional equations of continuity, momentum, sediment transport and bed morphology change, four equations are obtained for each time scale. By eliminating some terms based on typical field data, simplified sets of equations are obtained. Data from five estuaries at different evolution stages have been used to simplify the equations. Based on the simplified equations, four attractor states (in the terminology of system dynamics) are identified using method of equation analysis with some empirical knowledge. The attractors are defined in terms of relationships between the flow and morphology variables.
Year: 2011