Variations of sediment transport in theYangtze River
Yangui Wang, Xi Liu, Hongling Shi
Friday 3 july 2015
12:39 - 12:42h
at South America (level 0)
Themes: (T) Sediment management and morphodynamics, (ST) Basin-wide sediment management
Parallel session: Poster pitches: 15J. Sediment - Basin & Environment - Wetland
Human activities such as reservoir construction, water and soil conservation, and sand mining in river, frequently occur in the Yangtze River basin, and especially the Three Gorges Reservoir was impounded in 2003. These human activities result in variations of runoff and sediment discharge, which shows some changes in basin erosion and sediment transport in the Yangtze River. In order to study the characteristics of sediment transport in the Yangtze River, Sediment Transport Modulus (STM) and Incoming Sediment Coefficient (ISC) in the trunk stream and main tributaries were investigated in this paper with the cumulative curve analysis method and the Mann-Kendall test method. Here, the STM is sediment transport discharge in unit area above a river section, and the ISC is defined as the ratio of sediment concentration and discharge in river. Some results are as follows: (1) The STM and the ISC in tributaries depend on soil erosion, human activities and river conditions. The STM and ISC values in the Jialing River and the Hanjiang River are larger with serious soil erosion and great sediment transport intensity. (2) The STM and the ISC in mainstream depend on incoming water and sediment from tributaries and channel characteristics. The STM and ISC values fall in among values of the upper tributaries, and reduce gradually along the river distance. The STM and ISC values in the Jinsha River are greatest with the serious soil erosion and great sediment transport intensity. While in the Middle and Lower Yangtze River, the STM and ISC values are small with light soil erosion and low sediment transport intensity. (3) Due to comprehensive effects of human activities such as soil and water conservation and reservoirs construction in Yangtze River basin, the sediment trapping capacity increases. The STM in trunk stream and tributaries decrease with time, of which the STM values in Hankou station, Datong station, Hukou station in Poyang Lake and Waizhou station in Ganjiang River reduce slowly, and the STM values in the Jinsha River, the Jialing River and the Hanjiang River decreases obviously. (4) The ISC in the Yangtze River decreases with time because of comprehensive effects of human activities, which shows sediment transport intensity decreases and potential sediment capacity increases gradually with time, of which the ISC in the Hanjiang River decreases with greatest amplitude. The ISC attenuation law follows the exponential function.
