The Application Of System Dynamics To Planning Environmental Impact Assessment

Planning environmental impact assessment (PEIA) is a rising field in China, the responding theory, research method and apply of which are still on the beginning phrase. In the area PEIA, the environmental impact forecast is a very important part, the reliability of its result can directly affect the reliability of the environmental impact assessment. That is why to explore this problem more objectively and accurately. In the "technical principle of PEIA", China EPA framed some special prescribes and recommend using analogical method, system momentum, imput-output method and environmental mathematics model to analyze and forecast.Judging its characteristics of long time, excessive level, high-level nonlinear, dynamic of the county's master plan, it can not be describe and analyze with figures, which need a method with capability of macroscopical decision-making, a view to the whole system structure and an ability to hold its dynamic development to research this problem, while the system momentum is just a method that can possess of those advantages mentioned before.The SD is a quantitative analytical method assisted by computer emulator to research the complex social environmental system. Being its creation since 50's of 20 century, it has been applied deeply in science domain. One of the distinct characteristics of this method was its research field mainly concentrated on the area sustainable development andecosystem, the other was the background of its appliance basically taking large area and system as object. Comparatively, the appliance in EIA and small area especial in the county was seldom, saying nothing of the use in those two crossing field. At present, there were no literature and EPA case.This article took Gongxian in Sichuan master plan as example, using the system momentum as technique assistance, on the basis of area history, actuality investigate research and the analyse, we established a model to simulate dynamically the area plan implement and to forecast the environmental impact of the plan. The emphases were on tracking the creation, reduction and discharge of waste water, gas and rubbish, reflecting the mutual influence of the area social economy, environmental and resource and to use those researches to appraise the environmental reasonability of plan.The results showed that, with the implement of the plan, the area's social economy has been developed moderate and stable, the environmental quality improved; the value of the land resource incarnated adequately, the condition of the water resource shortage ameliorated thoroughly. The environmental impact of the plan was positive on the whole. The environment impact by the implement of the plan on the area was accepted, from the view of environment, the plan was reasonable.The model can embody the area characteristics well, the results from the forecast can be explained reasonably on the point of environment and have some reliability. As for the applicability of the method, it illuminated that the SD can not only apply in large area and sustainable development, but also a method with preponderance and applied value in analyzing the small area and in EIA.