Estuarial fine sediments make both positive and negative contributions to the coastal environment and present significant challenges to the conservation and management of water resources. This work's objective was to develop an improved fine sediment aggregation processes description based on governing sediment and flow characteristics. A combined statistical and deterministic representation of aggregation processes was combined with the one- dimensional convection-diffusion equation for multiple size classes. The number of two-body and three-body particle collisions was expressed by simple statistical relationships, using a new collision-efficiency parameter. Possible collision outcomes were used with collision theory to calculate the rate of sediment mass change for each class. Kaolinite and Atchafalaya Bay mud deposition experiments were conducted in a 100-m long flume. Significant variability in measured suspended sediment concentrations can be explained as intermittent perturbation and upward mixing of a high concentration stirred layer flowing close to the bed, below the lowest sampling point. The aggregation processes calculation method was found suitable for use as a primary component of sediment transport numerical modeling, but it is computationally intensive. Experiments showed that the number of three-body collisions in the estuarial environment can contribute significantly to aggregation processes in sediment suspensions.