Interaction between the braided bar and adjacent channel during flood: a case study of a sand-bed braided river, Brahmaputra-Jamuna

摘要

The braided river is characterized by numerous bars which exhibit chaotic nature and add uncertainty to understand and prediction of the river network. The development of these bars may be affected by several factors like boundary conditions, forcing and non-linear physical processes. Here, in this research, some prevailing physical processes which may affect the growth of bar after its emergence have been examined. Then, attempts have been made to identify the relationships between the bars and their adjacent channels. For this purpose, a two-dimensional-depth-averaged morphodynamic model, Delft3D was used to study the interaction between the braided bar and adjacent channel during a flood in a compound bar dominated area at a large sand-bed braided river-Brahmaputra-Jamuna. The results showed that the 2D model can reproduce the major physical processes which are responsible for the growth of the bar. The study showed that the size and shape of the bars were dependent on the characteristics of the adjacent channels. The occurrence of chute channel over the bartop during the flood depends on the depth of flow over the bar during the flood.