Study On The Water Environment Simulation In Chengqing Urban Rivers Of Three Gorges Reservoir

The paper is conducted on the basis of the research of Chongqing urban waterenvironment, which is a division of the study on the Three Gorges Reservoir’ sproblems of water environment.The Chongqing urban water environment is studied by using two-dimensionalsimulation. The two-dimensional model shows the distribution of flow field and CODconcentration after model equations，which are coupled by N-S equations, pollutantsdiffusion equations and biological attenuation equations, are solved with finitedifference method. The research has got more practical results when the parameters forthe model are identified exactly. There are four drainage outlets are selected for thetwo-dimensional simulation in ways of riverside discharge and center discharge, whichare Cai yuanba on the left bank of the upper reaches of Yangtze River, Shuangbei on theright bank along Jia lingjiang River, Gai lanxi on the left bank and Ji guanshi on theright bank of confluence river. Simulation results shows pollutants will have a largealong the bank in the way of riverside discharge and gathering zone’ longitudinal lengthis longer. The mixed pollutants zone is bigger in the way of center discharge, butconcentration is smaller than that in the way of riverside discharge. That means it’sbetter for the river’s health in the way of center discharge.Based on the model, areas of22mixed pollutants zones is calculated respectivelyby inputting design discharge of the most drying month in dry years, normal years andwet years. The data show it’s the biggest zone in dry year. Tao huaxi drainage outlet isbiggest one and Niu jiaotuo smallest in22mixed pollutants zones. The characteristicsof river where drainage outlet is located is an important factor for the area size of mixedpollution.The area size in straight river reach is smaller than which is in bend andnarrow river reach.According to the results of mixed pollution, the water environment capacity ineach month will be known by calculating along the length. This result has a richpractical meaning because it provides a foundation of directional guidance for theregion to the protection of water resources and water pollution control scheme of themaking and the environmental management.