A review on the study of transports of runoff-sediment-pollutant systems on urban surfaces

As a complex three-phase particle flow and the main carrier of non-point pollution, the coordinated transport processes and environmental effects of the runoff-sediment- pollutant systems on urban surfaces are very complicated. In this paper, the existing research on the transports of runoff-sediment-pollutant systems is summarized and analyzed from the perspectives of, the spatial-temporal distribution of urban surface sediment with absorbed pollutants, the hydrodynamic characteristics and simulation methods of urban surface rainfall-runoff, as well as the coordinated transport and reduction effects of runoff-sediment-pollutant systems. It is considered that the sediment dynamics theory can be used to study the urban surface sediment movement law during the rainfall-runoff process, and that the sediment deposition plays an important role in the reduction of particle pollutants due to the absorption effect. Finally, the following research actions should be carried out in the future: enlarging urban sample size; studying on dynamic characteristics of overland flow on different underlying surface; studying on incipient motion law for non-uniform sediment on urban surfaces, as well as sediment transport capacity for overland flow based on flow power theory.