A stochastic framework for modeling random-sized batch arrivals of sediment particles into open channel flows

摘要

Arrivals of sediment particles into open channel flows are typically simulated deterministically. However, there are random quantities of sediment particles brought into the open channel by natural phenomena such as rainfalls, landslides, mudflows, and dam breaches. As such, sediment particles may arrive at channel flow at random times in probabilistic quantities. Such arrival processes of sediment particles cannot be fully described without using probability. A stochastic framework that can account for the arrivals of random-sized batches of sediment particles into receiving waters is proposed. In this work, the random-sized batch arrival process of sediment particles is introduced to evaluate comprehensively the effects of particle arrival patterns, including random occurrences and random quantities of incoming sediment particles, on particle transport rates and sediment concentrations. Random arrivals are simulated as a Poisson process and the number of sediment particles in each arriving batch is described by a stochastic process that is specified in terms of binomially distributed random variables herein. The stochastic diffusion particle tracking model is used to simulate random trajectories of moving particles. Particle deposition and resuspension processes are considered. A probabilistic description of discrete sediment transport based on ensemble statistics of sediment concentrations and transport rates is presented. Simulation results are validated with experimental observations. Finally, time-dependent risks (i.e., probability of exceeding a pre-established turbidity standard with respect to time) are provided for decision makers to have a more comprehensive assessment for water quality management.