Study On Turbulence Diffusion Simulation And GIS-based Water Pollution Control Management System In The Three Gorges Reservoir Area

Water environment is a very complex system, which involves numerous information, such as pollution source, passive scalar transportation and disffusion in turbulence, watershed land-use, economic situation and the industrial distribution, monitoring sections, etc. The water environment is a dynamic process/system. So, how to make a high efficient management and analysis on the nemerous informations has become a hot research topic in the fields of water environment management. A hign quality Managemet Information System seems necessary. Turbulent flow and the pollutants disffusion are two very diffucult courses for the researchers to face, which have confused the world-wide researchers for a centry. This dissertation made an successful integration of GIS and Mathmatic Model-Base, and developed a GIS-based water pollution management and emergency reponse information system for Three Gorges Reservior Area(TGRA), Yangetze River, which delivered an adanced Spatial Decision Support System(SDSS). Fractal theory and analysis method were applied in turbulent water quality modelling. A fractal turbulence diffusion model was developed and uesed for the 3D water quality modelling in Wanzhou section of Yangetze River, with help of K-εtwo equation hydraulic model. The dynamics of the passive scarlar diffusion and transportation in turbulence was carefully studied. This Ph. D. thesis is one of the study outputs of the National Tenth-Five-Years Scientific and Techenical Research Project: Research and Demonstration on the Key techenologies for the Water Environmental Safty in Three Gorges Reservoir Area.A 3D K-εtwo-equation hydraulic model was applied for dynamics of the velocity in Wanzhou section of Yangetze River, Base on which the fractal turbulence diffusion model was developed and uesed for the 3D water quality modelling. A successful case of combination of fractal turbulent diffusion model and K-εhydraulic model has been showed, which is an innovation that fractal theory was applied to model compounded pollution area from multiple-sources in big and natural river system.In the development of the water pollution SDSS, Virtual Basic(VB) was selected as the software developing language, and ArcGIS Engine as GIS platform. A fully integration of GIS, Model Base, and Date Base was achieved, and consequently, a copyright-self-owned software was developed. The new software has several kinds of powerful functions for decision-making, including pollution source management, WWTP up-to-date monitoring, water quality query and assessment, velocity and quality modeling. The function of emergency response after the pollution accident happening was also enhanced in the software. The influent area from the pollution accident can be calculated and displayed out in time-serial.1D and 2D water quality models suitable for integration in GIS software have been developed. The compounded pollution area from multiple-sources can be simulated in big and complex situation river system through the developed models. The mathematical models have been validated by the existing monitoring data.According to the research result of 1D water quality simulation on the whole length of the Yangtze River in Chongqing area, the water quality of Yangtze River will be improved after finishing the construction work of the big dam with water level rising, if the main point-source pollution can be treated efficiently. The peak point of COD concentration will appear in the section between Chongqing main-town and Fuling city, which area has the high density of urban area, and is the main source district of domestic and industrial wastewater. While the peak sites of nutrient pollutants, such as NH3-N,TN,TP, will appear in the river section downstream to Wanzhou, where non-point source pollution, such as soil-erosion is heavy. After finishing the dam construction, COD concentration of TGRA will remain in ClassⅠorⅡ, NH3-N concentration will remain in ClassⅡorⅢ(the river section in Chongqing main town and near to the dam will remain in ClassⅢ). The concentration of TN and TP was predicted to exceed the desired water quality standard, and stay in ClassⅣorⅤ. The situation of TN is poorer than TP.According to the research results from 2D water quality simulation for the urban section of Yangtze River in TGRA, the near-bank water pollution belt in Chongqing main town will expand slightly, due to that the water level will not be influenced significantly; while in river sections near to dam or at the middle of the reservoir, the near-bank water pollution belt will minish obviously, especially when the water level is in 175m height.The 3D water quality simulation for Yangtze River in Wanzhou Urban area showed a very water quality gradient will appear in vertical direction of the Yangtze after the reservoir formed, and the turbulent mixing capacity will decrease at the bed of the river due to the low velocity. The surface water quality is relative poorer than the middle or bottom part. The near-bank pollution belt will be changed from narrow-and-long style to short-and-wide style. Through the model simulation, the width of the pollution belt will double, while the length will decrease slightly after the reservoir forming, comparing with the natural river situation with the same pollutant load.This dissertation selected TGRA as research area, and applied fractal theory into 3D turbulent diffusion in complex natual river,and developed a GIS-based software about water pollution management and emergency reponse. The research output is helpful to elevate the management level in the field of water pollution and emergcy response. The dissertation is a pioneer for the research on fractal application in the"nonregular"and"nonlinear"phenomenia like turbulent flow and turblent diffusion, which is meaningful to scientific research and actual use, aslo a good refernce for silimar revers or area.