Study On The Law Of Water And Sediment Transport And Regulation Measures Of Kunming Pool Water Diversion System

Because of the needs of urban construction and water supply in the riverside area,most of the projects have high water diversion rate.In order to ensure the supply of water in low water period,water diversion project must be built in broad and shallow river channels.There is a serious problem of sediment deposition after many years of operation of the diversion project,so the study of water and sediment calculation and control measures in the design stage of the diversion project is very important.Doumen reservoir project in Shaanxi Province is located at the site of the former Kunming pool on the right bank of Fenghe River in the western suburb of Xi'an city.The water diversion system of Doumen reservoir is composed of three parts:hydraulic dam,flood diversion channel on the right bank,dike heightening and thickening treatment on both banks of Fenghe River in the hub area,which is a typical arrangement of water diversion works.Taking the diversion system of Doumen reservoir as an example,this paper studies the law of water and sediment transport and regulation measures of the diversion system.The research process and conclusions have very important theoretical value and reference value for practical projects.Firstly,the research progress of river sediment at home and abroad is summarized.After that,the measured water and sediment data at the dam site section of Fenghe sluice are analyzed and counted,and the annual and annual variation trend of water and sediment is obtained.Then,the water and sediment are divided into different areas according to different flow levels and sediment concentration levels,and the water and sediment ratio of different areas is obtained,which provides a basis for the selection of subsequent regulation methods of water diversion system.Then,according to the actual project scale of Doumen reservoir diversion system,the existing unsteady and unbalanced sediment transport mathematical model is adapted and improved,so that it can be used for the prediction and calculation of sediment erosion and deposition of the diversion system in the case of water and sediment.Then,three basic calculation schemes are worked out for the operation mode of barrage dam and diversion channel,and the three different calculation schemes are respectively used to predict the sediment erosion and deposition by using mathematical models.Through the analysis and comparison of the calculation results,the reasonable operation mode of diversion system of Doumen reservoir is determined as follows:open discharge and sediment discharge operation of barrage dam in flood season,flood diversion channel in flood season is less than the boundary flow Quantity of water.Finally,by changing the selection of the limit discharge,the operation mode is further optimized,and the reasonable operation mode of the diversion system and the prediction results of sediment erosion and deposition in this mode are finally obtained.Based on the above work,conclusions can be drawn as follows:(1)The water and sediment from the dam site section of Fenghe River Sluice mainly come from the flood season,in which the water and sediment accounts for 49.7%and 70.7%of the annual average respectively.According to the statistics of different discharge levels and sediment concentration,it is concluded that the sediment is mainly concentrated in the water with large discharge and high sediment concentration.(2)A mathematical model of water and sediment for studying the operation mode of water diversion system is established,in which the model of sediment erosion and deposition is based on the theory of non-uniform and unbalanced sediment transport.In the process of establishing the model,we should fully consider all kinds of restrictions in the later stage of actual operation of Doumen reservoir,and then use the measured data to verify the model,and further calibrate various parameters,and finally use it to predict the process of sediment erosion and deposition.(3)Based on the comparison of the operation modes of the North pool of Doumen reservoir,three schemes are proposed for the whole year storage operation,the open discharge operation in flood season and the open discharge operation in flood season.Through the comparison of the calculation results of sediment erosion and deposition of the three schemes,the application mode is preliminarily selected as the open discharge in flood season,and the limiting conditions are further optimized.At last,the reasonable operation mode of Doumen reservoir water diversion system is proposed to be less than the limit flow(48m3/s).That is to say,during the flood season,only the period when the incoming flow is greater than 48m3/s will be used for open drainage,and the rest period and non flood season will be used for water storage.(4)The prediction results of flood open discharge operation in flood season are obtained by numerical simulation.After 56 years of operation,the accumulated siltation amount of barrage and sluice dam is 2.084 million m3,the accumulated siltation amount of flood diversion channel is 584 thousand m3,the average water flow into flood diversion channel for many years is 140 million m3,the sand flow is 3 million T,and the sand flow into North pool is 157 thousand t.