Modeling of Sediment Particle Deposition and Resuspension Processes Using a Stochastic Jump Diffusion Particle Tracking Model

摘要

Although river beds generally tend to reach an asymptotic equilibrium, it may be abruptly altered by occurrences of natural extreme flow events or establishment of man-made structures. These causes lead to significant morphological changes in the bed profile through erosion and deposition processes. The change of river bed can be quantified for predicting the stability of a river channel. The status of a geomorphological equilibrium can be determined by two transport phases, i.e., water and sediment transport. In particular, the bed profile in sediment transport models can be employed as the initial condition, and the calculated movement of sediment can set a new bed profile. Herein, we propose to use the stochastic jump diffusion particle tracking model (SJD-PTM) to simulate the movement of sediment and particle deposition and resuspension processes. The stochastic diffusion jump particle tracking model is a Lagrangian particle tracking model governed by stochastic equations. When simulating the particle trajectories from the mean drift, settling velocity, diffusivity and extreme events, we can calculate the probabilities of deposition/scouring of a sediment particle by comparing the particle shear stress with the critical shear stress. As the result, we can trace particles and obtain particle trajectories and their statistical characteristics such as the ensemble mean and variance. Furthermore, we will be able to simulate particle deposition and resuspension processes.