The study of water temperature and quality variations n a stationary pond

In order to deal with the environmental problems including the stench of retarding basin in summer and the damage of aquaculture basin caused by the cold current, we analysis the relationship between water temperature, BO (dissolved oxygen), BOD (biological oxygen demand) and vertical delaminate. Besides the diffusion effects of these physic parameters in the water were analyzed in this thesis. Based on upon statement we will produce the following analysis: 1.Regarding the water in retarding basin as one layer and analyzing the water temperature, the concentration of DO and BOD in summer and winter. 2. Regarding the water in retarding basin as two layers and analyzing the water temperature, the concentration of DO and BOD in summer and winter. 3. Observing the variation of water quality as pouring water into the retarding basin in summer. 4. Realizing the variation of water temperature in the aquaculture basin caused by pouring water during cold current. In this thesis, we have already obtained the analytical solutions of the water temperature in one layer at any time and in two layers at the infinite time. The analytical solution was put to proof the simulation solution which was modified from “computation method for dispersion with vertical layers” built by Kuo et al. at 2008. We concluded four primary conclusions. 1. The variation of the DO concentration was mainly affected by the BOD concentration and the water temperature in summer. However, the variation of the DO concentration was mainly affected by initial concentration and the BOD concentration in winter. 2. In order to simulate the 1D heterogeneous diffusion effect of the DO and BOD concentration, we assumed the water layer as two parts in vertical direction. Besides, the heat diffusion and convection coefficients in layer below are far lower than in layer upon. Based on the simulation results, we found the DO and BOD concentration will not be affected by upon assumption. The source term of governing equation is the primary parameter which affected the DO and BOD concentration in this assumption. 3. In summer, if the dissolved oxygen of the retarding basin decreased to the critical value or ratio, we could pour water into the basin to improve the amount of the dissolved oxygen. 4. During the cold current in winter, if we pour water into the aquaculture basin, the amount of decreasing velocity of water temperature will be reduced obviously.