| The propagation of a flood wave in a water-sediment system is investigated in this thesis. A refined nonlinear mathematical model composed of a fully coupled system of flow-sediment continuity and momentum equations and two closure formulas for sediment discharge and friction slope is proposed following a brief review of past work. Using the dimensional analysis, dominating variables in this problem are distinguished from dozens of flow and sediment properties in this flow-sediment system. Key dimensionless variables are identified and investigated. A matched asymptotic perturbation expansion is applied to explore the analytical solution of this model after a detailed introduction of the perturbation method. Layered solutions of wave and sediment concentration profiles are obtained downstream of an instantaneously released flood, which are composed of two distinct regions: an outer region where gravity and channel resistance dominate the flow, and a near wave shock region in which flow is controlled by convective inertia, pressure gradient, gravity and channel resistance. (Abstract shortened by UMI.)... |
