SEDIMENT TRANSPORT MODELING REVIEW―CURRENT AND FUTURE DEVELOPMENTS

With the rapid developments in numerical methods for fluid mechanics,computational modeling has become an attractive tool for studying flow/sediment transport and associated pollutant fate processes in such different environments as rivers,lakes,and coastal areas,over the past three decades,a large number of computational hydrodynamic/sediment transport models have been developed.The article traces the devel-opmental stages of current representative(1D,2D,and 3D)models and describes their main features,strengths,and limitations,and is intended as a first guide to readers interested in immersing themselves in modeling and at the same time sets the stage for discussing current limitations and future needs.The article provided model formulation,the spatial and temporal characteristics,the coupling/linkage of the hydrodynamic and sediment components,the model capabilities to handle unsteady flows,bed load and suspended load,sediment exchange processes,type of sediment(cohesive versus cohesion-less),and multi-fractional sediment transport.Some examples of the different model applications are summarized,the reader can use these case studies as a reference guide for model setup,calibration,and verification.The authors also attempt to provide an insight for model users about model choice,problem and way to improve model input and calibration.The article discussed model limitations such as simulating complex turbulent flows,sediment entrainment,multi-fractional transport rates,the treatment of the dispersion and diffusion coefficients,soil contributions from the bank or the hill slopes and floodplains,coupling between flow and sediment processes,and highlighted the future research needs for improving available hydrodynamic/sediment transport models.At last,the two-phase flow approach to formulate models of sediment-flow interaction and other cross-cutting issues are discussed and reviewed.