Guan, M. and Wright, N.G. and Sleigh, P.A. and Ahilan, S. and Lamb, R. (2016) Physical complexity to model morphological changes at a natural channel bend. Water Resources Research, 52 (8). pp. 6348-6364. ISSN 0043-1397
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Abstract
This study developed a two-dimensional (2D) depth-averaged model for morphological changes at natural bends by including a secondary flow correction. The model was tested in two laboratory-scale events. A field study were further adopted to demonstrate the capability of the model in predicting bed deformation at natural bends. Further, a series of scenarios with different setups of sediment-related parameters were tested to explore the possibility of a 2D model to simulate morphological changes at a natural bend, and to investigate how much physical complexity is needed for reliable modelling. The results suggest that a 2D depth-averaged model can reconstruct the hydrodynamic and morphological features at a bend reasonably provided that the model addresses a secondary flow correction, and reasonably parameterise grain-sizes within a channel in a pragmatic way. The factors, such as sediment transport formula and roughness height, have relatively less significance on the bed change pattern at a bend. The study reveals that the secondary flow effect and grain-size parameterisation should be given a first priority among other parameters when modelling bed deformation at a natural bend using a 2D model.