| Sediment is the problem which exists in all kinds of Hydraulic engineering. the design of preventing and excluding sediment is a key technical subject in the hydroelectric power station design, effects of preventing and excluding sediment are related to the security and stabilization of operating, and exertion of the hydroelectric power station's economic and social benefits. because of its unique development style, diversion type hydropower station are affected more easily by sediment problem, and the demand for preventing and excluding sediment is higher.Niyang River is a major tributary of the left bank of Yaluzangbu River, Niyang River basin is rich in hydropower resources, but the development of hydropower resources is very limited. at present, some small-scale development are made mainly in several tributaries, and mainly in diversion type.some power stations which have been built have serious sediment problem, and these problems have not been effectively addressed for a long time, even today many station is still in the "ill run", security of operation and electricity supply can not be guaranteed. therefore, on the basis of analyzing existed sediment problem in power stations of Niyang River basin, either on the existing hydropower station, or on the built hydropower station, proposing targeted solutions are of great significance.May 2008 to August 2009, on a combination of field surveys, visiting technicians of hydropower station, accessing to relevant information, i conducted a broad investigation to the existed sediment problem in the hydropower station of Niyang River basin. survey show that, as the changes of the annual runoff and the average sediment concentration is not large, leading to inter-annual changes in sediment yield smaller, but heterogeneity of sediment discharge during the year is very prominent, in July to September per year, the amount of sediment transport can be accounted for 76% to 93%; because of steep slope and rapid flow of the basin, in flood season, the capacity of carrying sand of water double, large bed-load accumulate in wide watercourse or the place in case of obstruction, and easily lead to mainstream swing or block the intake point of water diversion project, accordingly, seriously threat the leading water of hydropower station; compared to suspended load, bed load problem of hydropower station built is more serious, the phenomenon is not only with the basin topography, geology and unique water regime, sediment characteristics of the basin, but also with the location, layout, and operation and maintenance of anti-silt facilities of the power station.Against the sediment problem existed in the diversion type hydropower station of Niyang River basin, propose corresponding measures to solve the sediment problem, such as watershed soil erosion control, works site optimization, rational arrangement of preventing and excluding sediment etc. sediment problem of the hydropower station for teaching and practicing belonging to College of Tibet Agriculture and Animal Husbandry in Niyang River basin is very typical, the types of sediment diseases is comprehensive, and the sediment harm is serious, on the basis of analyzing the causes of sediment problem and sediment disease characteristics, referring to the management experience of hydropower station with similar sediment problems in other provinces, after analyzing the advantages and disadvantages of all kinds of anti-silt facilities, propose suggestive solution to this issue, which is based on the maintenance, renovation of existed anti-silt facilities, with minimal input for maximum economic and social benefits. due to lack of basic data, lack of funding and technical support, this study is only exploratory, research on sediment problem of diversion type hydropower station in Niyang River basin need to be further pursued.
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