BIMODAL SEDIMENT DISTRIBUTION AND ITS RELATION WITH THE RIVER ECOLOGY IN THE DADU RIVER BASIN
China is planning to transfer water from the upper Yangtze River basin to the Yellow River to ease the water shortage in northern China and solve the sedimentation problem in the lower reach of Yellow River. The Dadu River is one of the main source water sources for the project. To study the effects of water transfer on the river ecology, field investigations were performed for four main tributaries of the river on the Qinghai Plateau. Sediment, riparian vegetation and benthic invertebrate samples were taken. By analyzing these samples, the sediment is found to have a bimodal size distribution with one peak around 0.1 mm and another peak around 100 mm. The two peaks represent a suspended sediment load in normal years and gravel bed load transportation in great flood events. Sediment deposition with a bimodal size distribution provides diverse habitats for riparian vegetation and benthic invertebrates. Fine sand and silt deposit on the banks, bars and islands within the river channel provide soil for vegetation development. Gravel and cobbles depositing on the channel bed provide the best substrate for benthic animals to live. Moreover, cobble creates resistance to the flow and stabilizes the river channel. After the proposed water transfer, less great events will occur and sediment deposits in the riparian areas will change from having a typical bimodal distribution to having a normal distribution with one peak composed mainly of fine sand. The habitat in the downstream reaches will be affected. Correspondingly, the riparian vegetation will alternate and the numbers of benthic invertebrates will decrease strikingly.
Dadu River sediment bimodal size distribution riparian vegetation benthic invertebrates
Shimin Tian Zhaoyin Wang
China Institute of Water Resources and Hydropower Research, Beijing 100044, China State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China
国际会议
第16届亚太地区国际水利学大会暨第3届水工水力学国际研讨会(16th IAHR-APD Congress and 3rd Symoposium of IAHR-ISHS)
南京
英文
1049-1054
2008-10-20（万方平台首次上网日期，不代表论文的发表时间）