A Stochastics-based Bed Layer Model for Mass Conservation of Nonuniform Sediment

A new bed layer-type model for sediment continuity of nonuniform sediment is presented. The model is an alternative to the commonly-used active layer model. The discretization of the active part of the bed into a limited number of discrete bed layers is based on a probability density function of bed surface elevations. As such, the new model includes the effects of deeper bed surface elevations that are exposed to the flow less frequently. The material in the above three bed layers interacts with the flow and is subject to entrainment and deposition, whereas in the commonly-used active layer model only the material in the homogeneous top layer does. The new sediment continuity model is calibrated and verified based on three sets of flume experiments.