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Ecuador is located in South America, and sediment of CCS hydropower station is mainly volcanic ash. This paper makes a study on settling efficiency of sedimentation with the quasi-hydrostatic settlement method and unsaturated sediment discharge method. The result shows that settling efficiency of the two methods are close to each other. Further more, the paper makes a study on settling velocity in different calculation methods, including the method of hydraulic engineering design manual, Zhang Ruijin calculation method and method of the United States Army Corps of Engineers. The settling velocity of volcanic ash under the weak alkaline condition and the influences of temperature on settling velocity are studied by testing. It can provide a reference for design of hydropower station in the surrouding area of South America

On the basis of analyzing and evaluating the determining methods of dominant discharge, a drawback is pointed about four common methods. A new method to determine the dominant discharge is presented in this paper, which is appropriate to the Lower Yellow River. According to comparison, the coefficient frequency of discharge and sediment is more applicability and rationality, which provides the reasonable technique parameters for the river management of the Lower Yellow River.

Recent years, there were many piers constructed in tail reach of Yongjiang River. This made river channel in estuarial reach shrank gradually, which in turn influenced the shipping ability of estuarial area. Taking Qingshuipu pier that would be constructed in the left bank of Yongjiang river estuarial reach as an example, a numerical simulation have been done, and resistance parameter had been proved reasonably by author. The flow pattern, backwater height and channel scour-fill intensity near the pier trestle have been studied in different kinds of flood and tidal stencils. In engineering project, the trestle prevents flood from diffusing by dipping into the river. Meanwhile, backwater and deposition occur in the bank, which have impact on flow capacity. If the siltation in the area accumulates, then, point bar could not be scoured adequately in great flood period, which will force mainstream to move towards right bank. Based on the backwater and local scouring and silting situation near the pier trestle, the author puts forward a revised proposal and gains a preferable result. So, reasonable pier arrangement is the important condition for keeping steady and healthy to the tail reach of tidal river.

The 2-D water and sediment mathematical model which reflects silting in floodplain and scouting in main channel of over-bank flooding in the Lower Yellow River has been set up in this paper. Through carrying on 2-D water and sediment numerical simulation of the “96.8” typical flood, the author studied influence of over-bank flooding on flood travel and transverse exchange. The primary simulation results show that, adopting the over-bank flooding for silting in floodplain and scouting in main channel effectively guaranteed and expanded transverse exchange between floodplain and main channel and maintained the river channel vigor. This can relieve “secondary suspended river” states in the Low Yellow River to a certain extent; at the same time, the different magnitudes of over-bank floods have different effect of silting in floodplain and scouting in main channel.

Since the General Channel designed for the South-to-North Water Transfer Project in China has to cross many rivers and streams flowing from west to east, there are potentially serious effects additional flooding on the western side of the project alignment. Therefore, a 2-D numerical model for forecasting basin flood disasters was established and verified using historical flood data. The model was applied to researching the interaction between the proposed Project and flooding events for 5 streams in the Anyang River reach as a representative case study. Simulated results indicate that the model could correctly forecast the flood, submerged area and depths, and water surface elevations along the left side of the channel. The discharge capacity and location of hydraulic structures in the transfer canal alignment were analyzed. Then adjustments to the dimensions and positioning of proposed hydraulic structures were recommended at intersections, especially the addition of a channel to transfer flood water from one stream to another, which can effectively limit the sluice and protect the Anyang City from flooding.

Numerical seepage model of tailing dam based on finite-element method is established. By constructing special grid system and intermediate boundary conditions, combined drain seepage system (horizontal drain pipe + transverse- longitudinal blind drainage ditch) is well achieved in the model and the results of model analysis are verified by the results of experiments. Through the numerical simulation of the seepage in the tailing pond, seepage velocity field and seepage surface and water head distribution in both the transverse and longitudinal directions in different filling period and different drain seepage conditions have given. Analysis shows that water head change in slag accumulative area is relatively small and the local seepage slope is big in the dam-toe in the initial stage. As the increase of the filling height, the seepage slope increases correspondingly. The changing of the seepage field in three drain-seepage conditions is analyzed. After setting the combined drain seepage system, the seepage face is basically distributed along the drainage pipe. The seepage slope reduces obviously and meets requirements of the dam stability.

The Xiaolangdi Reservoir has entered the later sediment-retaining period, and new sediment transport phenomena and channel re-establishing behaviors are appearing. A physical model test was used to forecast the scouring and silting trends of the lower Yellow River. Based on water and sediment data from the lower Yellow River during the period from 1960 to 2012, and using a statistical method, this paper analyzed the sediment transport in sediment-laden flows with different discharges and sediment concentrations in the lower Yellow River. The results show that rational water-sediment regulation is necessary to avoid silting in the later sediment-retaining period. The combination of 3 000 m3/s