Niulan River Engineering Simulation And Water Quality Impact Assessment Dianchi Lake

Dianchi lake is China’s famous large shallow lakes on the Yunnan-Guizhou plateau, It is the sixth largest fresh water lake in China, kunming city, the north and south to distribution, the body assumes the bow lake, a carpenter to eastThe urban water supply, industrial and agricultural water, to regulate, flood control, tourism, aquaculture and other functions.Given because of the Dianchi lake in kunming city under along the FeiWuShui produced by urban development, with the rapid development of surrounding towns and urban expansion, the lake water quality become worse year by year.In the 20th century 60 years II for generation of Dianchi lake water quality, in the seventy s into a m class, water quality deteriorating in the late seventy s, basically down a level in a decade, since the 1990s the Dianchi grass sea and sea water are worse V, serious water eutrophication and cyanobacterial bloom all the year round, urban water supply function completely, has become a sustained, rapid and surrounding towns life quality improvement and social development of the restriction of the bottleneck, Dianchi lake in the ninety s was incorporated into national "sanhu sanhe" key management objects.In Dianchi lake water pollution situation of Dianchi lake watershed water pollution prevention and control has established "the sewage and the surrounding traffic, draw water diversion and water saving, regulation of rivers into the lake, agriculture and rural areas non-point source management, ecological restoration, ecological dredging and construction" six big measures, Niulan jiang-Dianchi lake filling water engineering for draw water diversion and water saving measures in the top priority, on September 25,2013, in water, to grasp the Niulan jiang-the nutrient content of engineering of the Dianchi lake Dianchi lake hydrating, changes in the water, this paper simulated prediction, the effect of water diversion work for Dianchi lake water environment management to provide technical support and decision support.This paper collected the Dianchi lake water quality and its measured data such as meteorological, hydrological, and considering the Niulan jiang-hydrodynamic and water quality of the lake Dianchi lake filling water project the influence of the ecological environment, choose Virginia institute of Marine research and development of Environmental Fluid mechanics EFDC (Environmental Fluid Dynamics Code) model is established in the Dianchi lake two-dimensional hydrodynamic and water quality model, simulate the Dianchi lake change process with time, and carries on the calibration, verification and inductive analysis.In this paper, the main research results are:(1)Using EFDC model to simulate the effect of Niulan jiang-Dianchi lake filling water project, a generalized Dianchi lake inflow boundary, simulation effect is good, the generalized is reasonable.(2)The Niulan jiang water quality in the Dianchi lake Dianchi lake filling water engineering improvement effect is obvious, but after the introduction of water diversion for a long time in the lake water quality spatial distribution, Dianchi lake j inning county southern waters near dead zones obviously;(3)This paper predicted results can be seen that the three rivers water diversion scheme is better than two rivers water diversion scheme, single river water quality in Dianchi lake, panlong river diversion scheme to improve the effect of the worst.(4)The spread of the water body will only along the shortest distance;So when in estuaries and west park in haikou river tunnel, Dianchi lake in southern hydraulic displacement occurs, there is almost no and lo river water when the water is converged on river panlong river to haikou, western tunnel during this short range, rather than from los dragon river to haikou river after a long distance, so want to replace water must be in the middle and lower reaches of Dianchi lake Dianchi lake downstream location opened into the river or water body does not generally flows through the area;(5)With the passage of time the water reaches an equilibrium state (in this model is considered to be around 10 months), even if again into the class III water effect on the improvement of the water quality is not large, if continuous injection will have a small area can achieve class III water;(6)The Dianchi lake area is large, large difference between two different regions of water ecological environment, different flow velocity, temperature, and sediment release quantity is different, lead to different regions has significant spatial difference between TN and TP concentration.(7)Through the model of two inlets for about 1 year of filling water engineering simulation can be seen that "Niulan jiang-Dianchi lake water diversion project", to improve the water quality of Dianchi lake has a certain effect, but to the whole class III water quality need also need longer time, but according to the simulation results, a year later the proportion of class Ⅲ water accounts for about 10% of the Dianchi lake, deduce from that, if other conditions are ideally (such as Dianchi lake pollution all contained, sediment to empty, etc.), one to two in estuaries of Dianchi lake water displacement in planning to Dianchi lake in 2020 the overall water quality is unable to achieve class Ⅲ.