Numerical Simulation of Flow and Suspended Sediment Transport in the Distributary Channel Networks

Wei Zhang,Qiong Jia,Xiaowen Chen

doi:10.1155/2014/948731

Abstract

Flow and suspended sediment transport in distributary channel networks play an important role in the evolution of deltas and estuaries, as well as the coastal environment. In this study, a 1D flow and suspended sediment transport model is presented to simulate the hydrodynamics and suspended sediment transport in the distributary channel networks. The governing equations for river flow are the Saint-Venant equations and for suspended sediment transport are the nonequilibrium transport equations. The procedure of solving the governing equations is firstly to get the matrix form of the water level and suspended sediment concentration at all connected junctions by utilizing the transformation of the governing equations of the single channel. Secondly, the water level and suspended sediment concentration at all junctions can be obtained by solving these irregular spare matrix equations. Finally, the water level, discharge, and suspended sediment concentration at each river section can be calculated. The presented 1D flow and suspended sediment transport model has been applied to the Pearl River networks and can reproduce water levels, discharges, and suspended sediment concentration with good accuracy, indicating this that model can be used to simulate the hydrodynamics and suspended sediment concentration in the distributary channel networks.

Highlights

Distributary channels are very common in the delta area, among which many junctions connect individual channel together to form the river networks system
The distributary channel networks model has been extensively calibrated with respect to the field measurements to optimize the representation of the water level, discharge, and suspended sediment concentration over the study area
The Nash-Sutcliffe model efficiency (ME) which is the ratio of model error to variability in observational data is employed in this paper to evaluate the performance of the distributary channel networks model

Summary

Introduction

Distributary channels are very common in the delta area, among which many junctions connect individual channel together to form the river networks system. In the late 1970’s, Thomas and Prashum [2] formulated the Hydraulic Engineering Center (HEC-6) model in a rectilinear coordinate and described it by using finitedifference schemes. This model was introduced for sediment movement under steady flows in gravel-bed rivers. Rahuel et al [12] developed a model to simulate the unsteady water and sediment movement in alluvial rivers. Wu et al [13] further refined this model to simulate the nonequilibrium transport of nonuniform total load in in the distributary channel networks. Fang et al [14] presented a one-dimensional numerical model for unsteady flow and nonuniform sediment transport in alluvial rivers. The model calculated the unsteady flow in open channels using the Preissmann implicit method and the Thomas algorithm

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Results

Conclusion