Variational-Based Data Assimilation to Simulate Sediment Concentration in the Lower Yellow River, China

Hong Wei Fang,Rui Xun Lai,Bin Liang Lin,Fang Xiu Zhang,Yue Feng Zhang,Xing Ya Xu

doi:10.1061/(asce)he.1943-5584.0001344

Abstract

AbstractThe heavy sediment load of the Yellow River makes it difficult to simulate sediment concentration using classic numerical models. In this paper, on the basis of the classic one-dimensional numerical model of open channel flow, a variational-based data assimilation method is introduced to improve the simulation accuracy of sediment concentration and to estimate parameters in sediment carrying capacity. In this method, a cost function is introduced first to determine the difference between the sediment concentration distributions and available field observations. A one-dimensional suspended sediment transport equation, assumed as a constraint, is integrated into the cost function. An adjoint equation of the data assimilation system is used to solve the minimum problem of the cost function. Field data observed from the Yellow River in 2013 are used to test the proposed method. When running the numerical model with the data assimilation method, errors between the calculations and the observations are ...

Highlights

The Yellow River is located in the middle of China, with a drainage area of 795,000 km2 and a length of 5,464 km (Fig. 1)
The heavy sediment load of the Yellow River always results in drastic fluvial processes and avulsion has become a major threat to human life and property
The study area is located in the lower Yellow River from Xiaolangdi to Gaocun, consisting of a distance of approximately 281 km (Fig. 1)

Summary

Introduction

The Yellow River is located in the middle of China, with a drainage area of 795,000 km and a length of 5,464 km (Fig. 1). The Yellow River is well known for its heavy sediment load and frequent shifts in its course. The lower reach of the Yellow River, downstream the Xiaolangdi Reservoir, has become a suspended river (hanging river) whose bed is higher than the surrounding land surface, in some locations by more than 10 m (Wang et al 2005). The heavy sediment load of the Yellow River always results in drastic fluvial processes and avulsion has become a major threat to human life and property. Climate change and human activities along the river make the sediment transport process more complicated (Lu et al 2013; Samaras and Koutitas 2014). To ensure the safety of levees, an accurate prediction of sediment concentration and water level becomes extremely important

Results

Discussion

Conclusion