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Physical complexity to model morphological changes at a natural channel bend
Author(s) -
Guan M.,
Wright N. G.,
Sleigh P. A.,
Ahilan S.,
Lamb R.
Publication year - 2016
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2015wr017917
Subject(s) - channel (broadcasting) , flow (mathematics) , sediment transport , surface finish , scale (ratio) , geology , geotechnical engineering , deformation (meteorology) , sediment , natural (archaeology) , grain size , flow conditions , series (stratigraphy) , mechanics , geometry , mathematics , geomorphology , computer science , engineering , physics , cartography , geography , mechanical engineering , paleontology , oceanography , computer network
This study developed a two‐dimensional (2‐D) 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 was 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 2‐D model to simulate morphological changes at a natural bend, and to investigate how much physical complexity is needed for reliable modeling. The results suggest that a 2‐D 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 parameterize 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 parameterization should be given a first priority among other parameters when modeling bed deformation at a natural bend using a 2‐D model.