2-Dimensional Vertical Water Temperature And Water Quality Numerical Simulation On Large Reservoir--Take Nuozhadu Reservoir As An Example

Water storage of reservoirs can bring comprehensive benefit of flood prevention, electricity generation, irrigation, shipping, water supply and fishery. Simultaneously it also has an environmental effect on varieties of aspects of river hydrology, sediment, topography and ecology etc. With the development of society and economy, a large amount of industrial wastewater and urban sewage untreated directly excludes into rivers and reservoirs. Thus it results to exceed the self-cleaning capacity of water body. The increasingly severe problem of rivers and reservoirs pollution poses a serious threat on survival and development of human beings. Though our country has abundant hydraulic resources, the exploitation of hydraulic resources far lags developed countries in the world due to the limitation of technique and economy conditions. More reservoirs and dams are under the construction or plan. Water pollution in our country is also quite severe. During the course of environmental impact assessment of water and electricity projects, water quality is often studied as a relatively important content. Therefore water quality analysis and forecast of reservoirs is the base of the environment assessment, plan, treat and management of reservoirs. The result of forecast will have vitally important significance.Nuozhadu reservoirs is located in the mid-downstream of Lancangjiang with a totaled capacity of 5850MW,with a yearly power generation of 23684Gwh, which is the biggest hydropower station in storage capacity, installed capacity and energy output of one year, is one of the main power supply station of transmission of electricity from the western to the eastern region and from Yunnan to other region. Besides generating electricity, it has the function of preventing flood, improving shipping and other synthetical benefits. Nuozhadu reservoirs belongs to multi-yearly storage reservoirs, and the norm operation lever is 812m, dam height is about 260m, corresponding, reservoir storage capacity is 223.68×108m3, regulating storage is 121.95×108m3. The construction of reservoirs will change the hydrology situation and environmental state of the reservoir area, and exert an importantinfluence to the rare fish, irrigating and living water in the section of downstream river of reservoir. Meanwhile stresses analysis of dam body temperature, temperature control of construction designing, the electromechanical aircrew cooling will were influenced by the construction of dam. So it is significant to predict water quality, temperature in reservoir before the hydropower station building, and also to the environmental protection andengineering construction.Main work and results of this paper are as follows:(1) To begin with, 2-dimension longitudinal and vertical-hydrodynamics, water temperature and water quality coupling concept model was established for common high-depth dam reservoirs, avoiding complicated turbulence k-ε model. In the water quality model 13 kinds of pollutant indices and their intricate relation were rationally considered. Secondly, in the calculation σ-shift was done at the vertical dimension, which irregular areas were converted to regular ones, so that corresponding conversion happened to water flow, water temperature and water quality model. Thus the calculation precisely accorded with free surface and boundary of reservoir bottom. Then arithmetic operators splitting method, staggered grid technique and alternation concealing method were introduced to disperse to colligating equations.(2) According to the characteristic of Nuozhadu reservoir belonging to high-depth reservoir of river dam, in this paper 2-demension hydraulic dynamics and water temperature method was applied to Nuozhadu reservoir. In terms of the unique condition of hydrology, climate and reservoir operations of Nuozhadu reservoir, a new turbulent diffuse coefficient was introduced, and the coordinate flex shift and vertical 2-dimension water temperature equations were combined. For Zuozhadu reservoir, reservoir region water temperature distribution and...