Modelling of flocculation and transport of cohesive sediment from an on-stream stormwater detention pond.

A new model to predict the transport characteristics of suspended sediment from an on-stream stormwater management pond is presented. It is based on Krishnappan's model of flocculated settling in still water, which was extended to dynamic conditions and verified by experiments with stormwater pond sediment in a laboratory rotating flume. The model was derived from first principles, but some input parameters, such as floc properties, had to be obtained by calibration, and input parameters describing flow field properties were obtained from a kappa-epsilon turbulence model. Simulated suspended concentrations vs. time and the size distribution of the flocculated sediment, produced with the calibrated model, agreed well with flume measurements.