Practical Study On Gray Forcasting Theory And Evaluation Methods In Water Environment

The Grey system theory was put forward early in 1980s by Professor Deng Julong, a famous academician of China. Over twenty years, the gray theory and method has been developed greatly in many fields and applied broadly in population, economy, zoology, agriculture, medicine, engineering, technology, meteorology, hydrology, geology and geological exploration. Why is it getting so popularly? In broad sense, people have been trying to know any systems whose inner structures and outside situations do not make sense by analyzing some appearing features of the systems, while the system with some information known and other information unknown or uncertain is so called Gray System. So getting a good grasp of the internal operation mechanism and the relevance between various factors of the Gray System is help for system control and management as well as policy-making. By specific way, the gray system exists all over the world, while the system that is absolutely white or black exists seldom. The Gray System Theory has given a series of totally new thought and study methods, including gray relevant analysis, gray system forecasting, gray cluster analysis and statistics, gray system planning and management. As the above ideas and methods are used broadly, Gray System has cause the disputation among the theory circles and the scientific & technical staff. In particular, the scientific & technical staff made further research in gray relevant analysis and gray system forecasting and also made the kinds of amendments about them, some of them are successful practices, some of them are inefficient cases. Therefore, how to regulate the applying domain and conditions of these two methods from the theoretical view is a valuable task not only in theory but in practice.((Pollution forming and transporting mechanism and environment effects ofwater environment in Bejing MiYun Reservior and upper reach (item No. G1999045700))) is the fifth subject of national important basic research and development planning program {The mechanism and regulation principle of air, water and land pollution in Beijing and around (No. Gl999045700) )) , while my paper is a part of the branch topic of the subject. Water environment is a kind of the systems closely related with the nature resources, the ecological balance and the social production activities. The evaluation and prediction on water quantity and quality are two major objects of study, which are also the topic that the hydrologists have been studying for long time. Reservoir , lake and river belong to water system of the earth surface, which is influenced by air raining and river converging. Furthermore. Water quantity and quality in reservoir are more easily influenced by outside factors and thus it has the uncertainty and random to the great extent. If using some defined method, you hardly describe the uncertainty and random; if using statistics to find the water distribution rule, you have to accumulate a large number of data. Till now, it is difficult to get a large number of monitoring data because of the limitation and difficulties of monitoring on the spot. Grey system which is famous for dealing with the chaos information can weaken the uncertainty and random of the original data by transforming observed data to form new sequence of data, from which we can find system law revealing the internal rule and mechanism from the appearing features which hide in the original data, thus we can analyzing or forecasting .In short, it is reasonable, feasible and efficient choosing Grey system as the mathematical approach to analyze and predict the quantity and quality of water in the water environment.By making a systematic study of Grey System Theory and Methodology, I have got to know it more completely. Moreover, I have made an effective adjustment to the weaknesses and shortcomings of Grey system theoretically, and also applied it in the program mentioned above .The major content includes in this paper as follow:1.Presenting the suitable conditions of using the classical GM (1, 1); (1)Because what the...