在研究水循环和水量转换规律的基础上 ,以城市为研究范围 ,找出影响水资源系统可持续发展的主要控制因素 ,建立水资源系统动力学模型 ,进行动态仿真模拟 ,并对模拟结果进行多因素的综合评价 ,从定量的角度说明政策在系统中的长期影响。本文以沈阳为例 ,运用该方法分析不同政策的实施对水资源可持续利用能力的作用和影响 ,为城市水资源合理开发利用提供科学的决策依据

Water is one of the most essential natural resources, especially for urban areas. Water shortage is a common problem confronted by many cities. A number of countermeasures, including saving, pollution control, seeking new water source, have been put forward to solve the problem. The purpose of this paper is to identify a better one from the measures and to facilitate sustainable use of urban water resources. Therefore, it is necessary to assess the effect of implementing the countermeasures. In order to achieve both conservation and effective utilization of water resources, a careful analysis of the region is very important. In the study, the relations among population, economics, government and ecosystem almost always constitute highly complex dynamic systems. That makes some common methods useless for solving the problem of the complex systems. So a holistic point of view is to be adopted and considerable amount of effort must be devoted to the analysis of water resources system (WRS) and strategy improvements. System Dynamics(SD), founded by J. W. Forrester in the 1950s, has been testified to be an effective way to the analysis of strategies and decision-making. In this study, SD is applied to quantitatively analyze and to synthetically assess the measures of urban water resources, in virtue of multi-factor general evaluation. Based on the research of water circulation and the law of water quantity transformation, within the fields of urban areas, this paper endeavors to find out the main dominant factor influencing sustainable WRS development, to build WRS system dynamic (WRSSD) model for dynamical simulation, and then to apply the multi-factor general evaluation to the simulation results. In this paper, WRSSD model is used in the WRS of Shenyang City as a case study. Four policies are taken into account: no-does, frugal use, pollution control, and sewage purification and reuse. Based on the quantitive analysis of the long-run impact of the measures, the effects and influences of different policies are fully clarified. The final result indicates that: (1) frugally use and pollution control are not enough, regarding the constant growth of water demand; and (2) the gray water will be an important part of water resources. The study can provide a scientific foundation for the rational development and utilization of urban water resources. The case study confirms the practicability and operability of the method. It indicates that SD model, in virtue of multi-factor general evaluation, is a useful tool for sustainable development of urban water resources.