Numerical Simulation Research Of Water And Sediment In Lower Reservoir Area Of Henan Tianchi Pumped Storage Power Station Based On MIKE 21 And MIKE 3

In recent years,in order to improve the operation status of power grid,a number of pumped storage power stations have been built all over the country.For the pumped storage power stations in areas with high sediment content in river,study on sediment problems will directly affect the loss of reservoir capacity and the abrasion of mechanical and electrical equipments.Lower reservoir of Tianchi pumped storage power station has many characteristics: large amounts of sediment of inflow,sediment is easy to deposit,the terrain conditions are not conducive to discharge sediments,no reservoir to intercept sediments,the problem of sediment in flood is very serious,the sediment problem of mechanical and electrical equipments is complicated,etc.Its sediment problems need to be studied as soon as possible.So,in order to ensure the safety of reservoir area and the normal performance of the project,it's necessary to carry out the research on problems of water and sediment in lower reservoir area of the Tianchi pumped storage power station.(1)Two dimensional and three dimensional mathematical model of water and sediment in lower reservoir area of Tianchi pumped storage power station are built by using MIKE software.And the model is verified by measured data and physical model test data.The validated results show that the model's simulation of the river channel's resistance has high accuracy relatively.The model can be used to simulate the flood routing and deformation of river bed in lower reservoir area.(2)Application of the two,three-dimensional model,the water and sediment numerical simulation of 50 year series process and typical frequency flood process has been carried out in lower reservoir area.In the long series of water and sediment conditions,sediment accumulation in lower reservoir area is delta deposit.Sediments are mainly deposited in the0.5~1.8km range of the front of dam.With the increase of time of reservoir operation,when the sediment deposition in front of dam has developed to a certain degree,it will develop along the original ? bend from the front of dam to the region near the water inlet and outlet.It will lead the increase of amounts of sediment deposition near the water inlet and outlet.In typical flood conditions,sediments in flood from the upstream of Huangya river will deposit in the lower reservoir area.It also mainly deposits in the 0.5~1.8km range of the front of dam.Meanwhile,partial sediments will develop along the original ? bend from the submergeddam upstream and the front of dam downstream to the region near the water inlet and outlet.The phenomenon will be more obvious when the flood is greater.(3)Aimming at the problems in the design of sediment reduction,the research makes modified design of increasing the height of the submerged dam upstream and adding new submerged dam downstream.And the modified design has been carried out in the special numerical simulation of water and sediment.The calculation results show that the modified design reduces the development of sediment deposition from the front of dam to the region near the water inlet and outlet better.And the amount of fine intercepted sediment in surface water of the left river increases.It leads the decrease of amounts of sediment deposition near the water inlet and outlet.Meanwhile,it increases the amount of sediments discharging to downstream by sediment discharge facilities.The ratio of sediment deposition's reduction is more than 4%.The modified effect is also reflected in the physical model test.It has a certain referenced value for the design and planning of similar pumped storage power station.