Two-dimensional modeling of channel evolution under the influence of large-scale river regulation works

Abstract

In the middle and lower reaches of alluvial rivers, various kinds of river regulation projects affecting natural channel evolution often are distributed due to the requirements of flood control, navigation, and channel stability. However, the influence of large-scale river regulation works on fluvial processes is not fully known. Therefore, a two-dimensional (2D) morphodynamic model has been improved to address this problem. The new detailed procedure is presented in this paper: (i) First, each node in the study domain was labeled using a specified point code to distinguish the zones with or without regulation works; and (ii) second, a 2D model was improved to consider the effect of river regulation works. In the refined model, the modules of sediment transport and bed deformation were treated separately in different zones. In the unprotected zones, both bed deposition and erosion were likely to occur. In the protected zones, bed erosion could not occur owing to the protection provided by the river regulation works, unless there was a deposition layer newly formed over the previous simulation periods. The observed data of the years 2004 and 2008 were used to calibrate and verify the improved 2D morphodynamic model which was applied in a 68-km-long reach of the Middle Yangtze River. Satisfactory results were obtained indicating that the improved model can better simulate the process of sediment transport and the morphology adjustment in three central bars in the study reach.