Sediment settling velocity in the water is a sign of important physical quantities of sediment movement characteristics. Sediment concentration has a significant impact on the settling velocity. On the one hand,in the process of settlement,Single particle of sand would arose the movement of circumambient water. Because of the existence of other sand, circumambient water is blocked and loses the freedom of movement. Its equal to increase the water viscosity. And this makes the settling velocity lower. On the other hand, sand in the process of settlement brings along the circumambient water, and that goes with the sand down, and this makes the settling velocity bigger. Moreover, the existence of lots of sands will augment the turbid water density, and increase the buoyancy of every sand and finish its settling velocity. This paper states and trims the experiment data of the yellow soil at Station Hua yuankou and Fly-ash in Zhengzhou Power Plant, Using the Robertss experiential formula and Kynch experiential formula, the turbid water thickness and the time it needs are computed. After contrasting of the computed results, we have known that the laws which Fly-ash follows better than the silt.

No abstract

Zhenshui is the biggest tributary of Xiaolangdi Reservoir, and its original storage capacity is 1.767 billion m3 and accounts for 33.5% of the tributary. By October 2013, the amount of sediment in Zhenshui reached 0.2365 billion m3, and the sand bar was 5.78m in height. Influenced by operational mode of reservoir and terrain, the formation of sand bar at Zhenshui estuary has certain inevitabilities. The sand bar can prevent water and sediment exchange between mainstream and tributary, and the internal storage capacity of tributary is not effectively used. Analyzing sand bar and its cause can supply some technical supports for prevention.

According to datas of Sanmenxia Reservoir and physical model test of Xiaolangdi Reservoir during later sediment retaining period, the paper study evolvement of high beach and deep channel of reservoir in the sediment-laden rivers. The results show that: 1The evolution of high beach and deep channel is as follows, firstly, beach and channel increase synchronously , and then scour happens in channel. Channel scour and scour amount is crucial to form high beach and deep channel. 2It is found that tributaries were equivalent to the horizontal extension of mainstream riverbed. The deposition process of tributary is closely related to many factors of natural topographic condition, deposition morphology of mainstream at the confluence area of mainstream and tributary and so on. The cross-section of tributary kept uplift horizontally, and sand bar has formed in some tributary estuary. 3Rainfall erosion formed in flood period is beneficial to forming hyper-concentrated flow, to a certain extent; it can recover channel storage capacity, and play an important role on utilizing long-term comprehensive benefits. Studying evolvement of high beach and deep channel can supply some technical supports for regulating operational mode of Xiaolangdi Reservoir during later sediment retaining period and prolonging service life.

The simulation test on the late sediment storage period in shaping program of high floodland and deep-cut channel on the Xiaolangdi reservoir, and the evolution of high floodland and deep-cut channel, for the Xiaolangdi reservoir sediment retaining period reasonable reservoir operation mode, provide reference for reservoir extending service life.The study shows that:①Formation of High floodland and deep-cut channel evolution, which based on the beach sediment uplift and slot synchronization channel and then washed down the process, whether the erosion and scour quantity to whether can form high floodland and deep-cut channel topography is essential;②The tributary of the riverbed is equivalent to extending transversely, tributary river sedimentation process and topographic condition and tributary junction of the main river deposition pattern and process and other factors are closely related, tributary cross-sectional deposition morphology is mostly parallel to the raising tendency, department branch flow entrance there was a sandbar;③the reservoir during the flood period rainfall scouring camera, in favor of hyperconcentrated flow is generated, to a certain extent, recovery tank capacity, play long term use of reservoir.