Application Of Similarity Methods To Comprehensive Evaluation Of Water Environment

Water as a special resource, which sustains all life, is the substance of sustainable development society. With the rapid development of economy and growth of population recently, the problem of water resources shortage, water environment deterioration, drought and flood becomes more and more acute. Firstly introduce the review of study on the methods of comprehensive evaluation of water environment and similarity method. Then establish following models of comprehensive evaluation of water environment based on similarity methods: (1) A method of uneven weight distance coefficient used for calculating the similarity degree was put forward, and a new model was established based on the maximum information entropy principle used for dealing with the weight randomicity. (2) Using weighted proportion instead of weighted generalized distance based on similarity theory establishing a minimum goal functiom, a new fuzzy pattern recognition model was presented based on introducing Jaynes's maximum entropy principle to depict the objetive influence of uncertainty. In the modeling process, accelerating genetic algorithm was introduced to ascertain the model parameters objectively. (3)Choosing the evaluation methods to make combination based on similarity theory and endowing each evaluation method with corresponding weight based on how much information it contained, then accelerating genetic algorithm was used to ascertain tne model parameters objectively, at last the similarity theory was used to checkout rationality, a new weighting combinatorial evaluation method based on similarity theory was presented. The connection degree of set pair analysis can be regarded as the similarity degree of a set pair, then a model for evaluation of water quality was developed based on set pair analysis, which overcomes the drawbacks of traditional evaluation methods.The application results indicate that the possibility and reliability of the models applied to water environment system engineering was obtained. It is concluded that the models stated above can be applied to water environment system engineering generally.