| System Dynamics (SD) falls into the category of Systems Science. It regardes the research object as a system, and analysises the system's functions through its internal structure, it combines natural science and social science, adopts qualitative and quantitative to analyse the system comprehensively. Eco-environmental system is a multi-factor, high-order, non-linear complex system, involves many complicated factors. So, traditional research methods are no longer applicable to such complex systems.Therefore we chose System Dynamics to study the problem of eco-environment system in Chongqing in the background of conducting urban and rural development, hoping to simulate and forecast the evolution of its begaviors and carry out policy experimentation on it.This paper is mainly divided into four parts, the first is the evaluation research on present urban eco-environment in Chongqing city in the background of conducting urban and rural eco-environment development. And then, the behaviors of eco-environment system during 1998 to 2008 in Chongqing city was empirically evaluated by using Times Series Analysis & PCA method. The results showed that the overall level of eco-environment quality in Chongqing city in the context of urban and rural development has continued to rise, and the changing rates changed up and down in the meantime. The coordination degree variations of the system showed a double peaks curve:it increased steadily with a low-rate from 1998 to 2001;and then it reached the first peak of 0.5238 in 2001, there is a sudden sharp decline (evaluation index of-1.3478, inter-annual variation scope of -1.8715) in 2001, and gradually evolved to the bottom, then it started to rise again with a more rapid rate (the average inter-annual growth rate is 0.7259) in 2001. Its evolution reached to the second peak 0.7749 in the year of 2006 and began to decline. The relationships between subsystems of urban and rural eco-environment in Chongqing city can be characterized with the equation F= 0.7456F1-0.73112.The second part is the research on dynamic model of eco-environment system in Chongqing city. By means of system dynamics theory and methods, this paper analysises the eco-environment of Chongqing city in the background of coordinating urban-rural development. From the analyzation, the paper believes that the system consists of three major state variables:pollution, population and funds. They are interrelated and interact on each other through other state variables and auxiliary variables. Thus the system constituting many feedback loops which have different polarity. For that point, this paper has established the System Dynamic model of eco-environment system of Chongqing city in the background of coordinating urban-rural development, and then estimated the model parameters and determined the model kinetic equation. The simulation and final test of the model indicate that its structure and historical behaviours are well testified. So, the model can well describe the actual system.The third part is System Dynamics simulation for study on eco-environment system of Chongqing city and the results show that:(1) In the next nearly 10 years, the city's total population will increase to 38.6014 million; the urban population will increase to 24.7821 million; the agricultural population will gradually reduce to 13.1283 million, the urbanization rate has reached 0.642, a substantial increase is in industrial output, the process of rapid urbanization has been improved quickly. In the context of urban and rural development in Chongqing Municipality, the total pollution in the environment of industrial waste pollution is greater than the proportion of agricultural non-point source pollution, it is relatively small. (2) As a whole, the industrial waste pollution in Chongqing is a water-based pollution; however, from the view of the rate of increase, it is a gas-based pollution. Taken together, the city's current pattern of industrial waste pollution is: "waste water pollution"> "air pollution"> "solid waste pollution". Among them, industrial solid waste pollution are "ash" pollution type, air pollution is a "sulfur dioxide and fuel dust" pollution type. (3) From the total pollution of view, agricultural non-point source pollution in Chongqing is "cultivation-pesticides-fertizer" pollution type, as for the pollution, planting causing is more serious than cultivation causing. Among planting pollution, pesticides and fertilizers pollution is the most serious one. and then is the straw pollution, the plastic film pollution is the smallest one. However, view at the increasing rates of pollution, it is "pesticides-fertizer-cultivation" pollution on the basis of planting pollution, pesticides-fertizer pollution increase is the fastest, and then is the farming and straw pollution, farm plastic film pollution is relatively minimal.The fourth part is the policy pilot studies to ecological environment system dynamics model of Chongqing, considering the year of 2010 as the policy test starting point simulate the model. Results show that:(1) To coordinate the development of urban and rural areas in Chongqing's, we must strictly control the population and capital these two factors, so as to coordinate the development of urban and rural eco-environment. As for the total population, first is to control the total population to reach 38.3157 million; second is to gradually increase the urbanization rate to about 0.698; as for the capital element, particular attention should be paid to controlling the ratio of investment in agriculture so as not to indirectly caused increased agricultural non-point source pollution. (2) In order to control the industrial waste pollution occurring in cities and towns,we must pay attention to adjusting the industrial structure, and at the same time, improve the rates of pollution disposal and resource recycling, reduce energy consumption; optimizing simulation showed that the living sewage in the system should also be paid sufficient attention and be reduced by 40% or so on the basis of the basic scheme. (3) The control of agricultural non-point source pollution should focus on the emission of pollutants and pesticides, farming fertilizer application, and increase the effective processing and use of pollutants and pesticides. Optimization scheme showes that they should be gradually improved at 10%-15%. |
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