Sediment transport modeling review—current and future developments

With the rapiddevelopments in numerical methods for fluid mechanics,computational modeling has become an attractive tool for studyingflow/sediment transport and associated pollutant fate processes insuch different environments as rivers, lakes, and coastal areas,over the past three decades, a large number of computationalhydrodynamic/sediment transport models have been developed. Thearticle traces the developmental stages of currentrepresentative(1D,2D, and 3D)models and describes their mainfeatures, strengths, and limitations, and is intended as a firstguide to readers interested in immersing themselves in modelingand at the same time sets the stage for discussing currentlimitations and future needs. The article provided modelformulation, the spatial and temporal characteristics, thecoupling/linkage of the hydrodynamic and sediment components, themodel capabilities to handle unsteady flows, bed load andsuspended load, sediment exchange processes, type of sediment(cohesive versus cohesion-less), and multi-fractional sedimenttransport. Some examples of the different model applications aresummarized, the reader can use these case studies as a referenceguide for model setup, calibration, and verification. The authorsalso attempt to provide an insight for model users about modelchoice, problem and way to improve  model input and calibration.The article discussed model limitations such as simulating complexturbulent flows, sediment entrainment, multi-fractional transportrates, the treatment of the dispersion and diffusion coefficients,soil contributions from the bank or the hill slopes andfloodplains, coupling between flow and sediment processes, andhighlighted the future research needs for improving availablehydrodynamic/sediment transport models. At last, the two-phaseflow approach to formulate models of sediment-flow interaction andother cross-cutting issues are discussed and reviewed.