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| Applicability and modifications of the Nemerow index method in evaluating environmental quality |
| Received:April 10, 2017 |
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| KeyWord:Nemerow index method;environmental factors;applicability of methods;modifications of methods;weights of pollution factors |
| Author Name | Affiliation | | HAN Shu-xin | Shandong Analysis and Test Center, Ji'nan 250014, China | | WANG Li-hong | Shandong Analysis and Test Center, Ji'nan 250014, China | | ZHAO Chang-sheng | Shandong Analysis and Test Center, Ji'nan 250014, China |
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| Abstract: |
| In order to study the applicability and modifications of the Nemerow index(NI) method used for evaluations of environmental quality, mathematical derivations were performed based on the original formula. The results showed that the formula of the NI method could be transformed into a linear equation. The slope and intercept of the equation could be the weight coefficients of the maximum value(Fj,max) and arithmetic mean value(Fj,ave), respectively. With increases in the ratio of Fj,max to Fj,ave, the weight of Fj,max increased while that of Fj,ave decreased. The number of pollution factors(n) participating in the evaluation had a significant influence on the results. The NI method was found to be more suitable for evaluation of environmental factors with clear purposes and directions, or those associated with low pollution in a region. In order to improve the applicability of the NI method, some modifications were proposed for two revised Nemerow index(RNI) methods. For the Ⅰ-RNI method, n=5 was used as the partition node, and the ratio of Fj,max to Fj,ave was equal to five for the Ⅱ-RNI method. The Ⅰ-RNI method was used to evaluate factors with clear purposes and directions, and those associated with less pollution; the Ⅱ-RNI method, an extension of the Ⅰ-RNI method, was more suitable for multifactor comprehensive evaluation. Based on the mathematical connotation of the linear equation for the NI method, when n or the ratio of Fj,max to Fj,ave is not more than 5, the original NI method can be used without affecting the objectivity and accuracy of the evaluation results. |
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