Study On The Theory And Method Of Comprehensive Evaluation For Urban Water Security

Water resources of China is not only scare and non-balanced distribution, but also polluted very severely, and it has become the key obstacles for the sustainable development of China. The comprehensive evaluation for urban water security is the foundation for designing the strategy and plan of urban water security, and it is also a new research area, so it is very important to study the comprehensive evaluation of urban water security whether for theory or for practice. The contents and results of this thesis are just as follows:Firstly, the concept and the properties of urban water security are defined. And the developing tendency of water security status for human-water complex system is analyzed based on the entropy theory of dissipative structure. On the base of that, the concept of bearing capacity of urban water security is creatively brought out, and its influence factors and calculating methods are discussed. From the aspect of pressure index and support index, the comprehensive evaluation index system for urban water security is set up.Secondly, for the comprehensive evaluation of urban water security has the properties of complex, fuzzy and multilayer, and the traditional evaluation methods with fuzzy sets do not take the middle information into account, the comprehensive evaluation model is brought out based on the vague sets. How to determine the vague value of index is discussed, and Multi-AHP is used to determine the weight of index. As an example, Beijing, Tianjin, Shanghai and Chongqing's urban water security are estimated by the method, and the effectiveness of it is proved.Thirdly, forecasting model for urban water demanding based on RBF is established, and in order to improve the converging speed and precise of RBF network, simulated annealing-genetic algorithm is used to optimize the network. At the same time, a combination-forecasting model based on rough set is brought out to improve the precise and reasonability of forecasting results. On the base of that, from the aspect of absolute index of water security, the water balance between the demand and supply is analyzed, and according to different water using scenario, the situations of water demand and supply of Tianjin in 2007 and 2010 are analyzed.Finally, for the traditional comprehensive methods did not take the space geological properties into account, so GIS is used to discuss the digitalization and visualization of comprehensive index, therefore a urban water security comprehensive evaluation method is brought out supported by GIS. The scheme of Decision Support System of urban water security is designed. And the water security status of 15 cities in Huabei is researched. The study of this thesis can supply scientific accordance for visualization decision for urban water security.