Suspended Sediment Rating Curve Of The Yangtze (Changjiang) River: Characteristics, Interpretations And Practices

The present study relies on the well-measured suspended sediment loads that play an important role in both academic study and engineering applications, especially in the coastal areas. Generally, suspended sediment loads can be calculated using discharge and suspended sediment concentration data. However, it is usually not easy to measure suspended sediment concentrations, because methods used for measuring suspended sediment concentrations are either expensive or complicative. Suspended Sediment Rating Curve (SSRC) has been widely used in predicting sediment concentrations, which are necessary for suspended sediment load predictions. However, temporal and spatial variabilities of the SSRC restrict its applications, especially in a huge river catchment with indefinite boundary conditions, such as the Yangtze River catchment. In order to make a full use of SSRC, it is important to have a further understanding on the characteristics of the SSRC, driving forces behind these characteristics, as well as their implications on the hydro-morphological features. This study aims at the characteristics of SSRC along the Yangtze River, in order to explore the mechanisms and interpret the implications of SSRC on hydromorphologic features of the Yangtze, and to discuss the proper SSRC in relation to prediction of suspended sediment concentrations.Based on SSRC from 10 hydrological gauging stations (Cuntan, Wanxian, Yichang, Zhijiang, Xinchang, Chenglingji, Luoshan, Hankou and Datong) along the Yangtze River, this study indicates main characteristics of SSRC.Firstly, the power-relationship between river discharge (Q) and suspended sediment concentration (SSC) varies between different reaches of the Yangtze. Power-liknage between Q and SSC is better reflected in the upper reach of Yangtze, with an average value of R~2 >0.85. The R~2-value decreases downstream through the Yangtze. However, the lowest value of R occurs in the middle reach with a value of 0.0542 at Chenglingji and 0.4664 at Luoshan. Average values of R~2 from Hankou and Datong gauging stations, which are located in the middle and lower reach of the Yangtze respectively, are around 0.75. The lowest R~2 -values occur in the middle reach of the Yangtze (also known as Chenglingji-Luoshan reach). In this reach, SSC value even decreases with increasing discharge. The lower correlation between Q and SSC at the Chenglingji-Luoshan reach is largely afftected by Dongting Lake.Secondly, characteristics of SSRC and the hydromorphology can be well...