Seite - 357 - in Book of Full Papers - Symposium Hydro Engineering

6. CONCLUSIONS Using dimensionless multiple regressive analysis and sensitive analysis, some conclusions can be get: (1) The evolution of sand bar in the river mouth of those tributaries in Xiaolangdi reservoir area, is related to the water and sediment conditions, local terrain factors in the tributaries and main channel, location of the front of the delta in the reservoir area and others. Among them, the location of the front of the delta is the most sensitive factor; (2) For engineers, the aim is to limit the evolution of sand bar and utilize the depositing capacity in those tributaries in the reservoir area. According to this paper, these actions are effective: increasing the sediment concentration flowing into the reservoir in flood season, decreasing the grain size of bed material load, increasing the gradient of the main channel, increasing the relative width of the river mouth of those tributaries. Specifically, increasing the relative width of the river mouth is recommended, which can not only limit the evolution of sand bar, but also increase the depositing volume in the tributaries. ACKNOWLEDGEMENTS This study was supported financially by the National Science Foundation of China (Grant No.51509102,51679104, and 5153000441). REFERENCES Hu Chunhong and Zhang Zhihao (2006).Evolution and control of estuary sandbar in Yellow River responding to variation of flow-sediment condition. Journal of Hydraulic Engineering, 37(5): 511-517. Li Jiufa and Ji Zhong (1988). The statistical analysis on the sedimentation variations in the south passage of the Changjiang River estuary caused by the flow and sediment conditions. Journal of Sediment Research, (4): 76-82. Li Shanzheng, Chen Zongwen and Zhang Qishun (1985). Sediment problems of Guanting Reservoir. Journal of Hydraulic Engineering, 16(3): 10-21. Li Zegang (1997). Formation and evolution of the bar on Yellow River estuary. ACTA GEOGRAPHICA SINICA, 52(1): 54-62. 357