Bed Topography in Shallow River Bends

摘要

A mathematical model of the flow, bed topography, and grain size variation in curved alluvial rivers is presented and analyzed with the purpose of obtaining insight into the governing physical processes. The model consists of three sub-models, viz, a depth-integrated flow model, a sediment transport model, and a sediment budget model. Computational results of the mathematical model are compared with measured data from various laboratory flumes. The flume experiments considered have been selected in such a way that a variety of hydraulic conditions and geometries are represented. The general conclusion is that the mathematical model, with proper calibration, can simulate the bed topography and flow distribution very well. Also the overall grain size distribution of the bed can be simulated qualitatively, whereas quantitative prediction is impeded by shortcomings in the description of the sediment transport per size fractions close to initiation of motion.