The Research And Application On Grey System Theory In The Environmental Assessment, Planning And Management

Although, at present, there are lots of methods of environmental assessment, environmental planning and environment management, the methods, which are applied in the complex environmental systems, which have multi-level, multi-level, multiple affecting factors, but lack of data and information characteristics, are still in researching stage. In recent years, facing complex of environmental systems and lack of relative data, some scholars have been researching in the uncertainty problems thoroughly and widely.Data samples incompleteness composes the basic feature of grey system theory. As a result, research on environmental mathematical model based on grey system theory, plays a very important role in application in environmental systems analysis having lack of data and information. Compared to other methods, the favorable adaptability and flexibility grey system theory is useful in existing environmental analysis assessment, environmental forecasting and planning, environmental management decision-making, etc.This subject attempts to research the basic principles and basic relative modeling method, and applies them into environmental assessment, environmental planning and environment management. The subject research and application are discussed in detail from the following five aspects:1. The method of grey relative analysis is used to ascertain compare sequence and reference sequence, and environment quality sub-indexes weighted are applied in the grey relational degree analysis in order to gain the environmental pollutant valuation indexes, and then the related degrees are calculated and analyzed, after sequenced and compared, the conclusion is get at last.2. The method of grey clustering is used to construct the whitening functions, and functional values are solved, subsequently clustering vectors are constructed, after compared, environmental elements are classified according to ranks.3. Situation decisions are built by means of grey decision making model, after the effect whiten values under all kinds of objectives and situations analyzed, situation effect measurement and comprehensive effect measurement are calculated, thus multi-goals problems are transformed into single goal problems, at last the decision is made by the best situation selected.4. According to grey system theory, the grey differential equation of h variables and n orders is derived so that the grey differential equation composed of grey data sequences of 1order is gained, as follows:(dx¹)/(dt)+ax¹=uThen grey forecasting model is fit as: (?)¹ (t+1) =[x⁰(1) -u/a]×e^-at+u/a, and then (?)¹is reduced into x⁰, and relative error E⁰and medium value error e_1/2 are solved, if the conclusion is not satisfying, the model constructed has to be adjusted again and again till the conclusion is satisfying. The environmental situations are forecasted quantitatively by means of the grey forecasting model.5. The objective function of environmental mathematical model of grey predictive linearprogram is: f (x) =sum from j=1 to nCX;The corresponding restricted conditions are:sum from j=1 to n a_ijX≤B, (i=l, 2,......m) ,X_ij≥0, (j=1, 2,......n)As B in the above formula is of grey time-series features, the model of GM (1,1) is used to solve the corresponding forecasting values, and then the ones are substituted in programming model to solve the programming solution of problem under corresponding restricted conditions.After the grey system theory and the constructing methods of five kinds of grey models are studied in this paper, they are applied respectively in environmental quality assessment, the environmental management decision-making in a wastewater treatment plant, water quality forecasting and the air environmental planning so as to evaluate and appraise the effect and use value.