Objectively Evaluating Environmental Comprehensive Quality by Improved AHP Method

Calculating arithmetic weighted average value of environmental quality comprehensive index is a common method in environmental quality comprehensive evaluation. The relative importance of each pollution factor in the Analytical Hierarchy Process (AHP) method comes from pooling expert opinions in general. Because expert opinions are based on their information and judgment criterion, it may lead to the uncertainty of determining weight. In order to overcome this uncertainty, an improved AHP method is developed. The process of the improved AHP method involves the following key procedures. First based on the environmental monitoring data of pollution factors two parameters yil and yi2 are calculated. Second the pollution factors are put in order according to the combinations of symbols and values of yi2 and yi2. Third the odd integers are given to pollution factors in light of seating order of factors. And forth the factor weights are achieved by the judgment matrix formed on the pair- wise comparison of factors. This shows that weights of pollution factors are completely related to the objective monitoring data through a standardization of procedure by the improved AHP method. The environmental comprehensive quality of sediment in Qinhuai River, Nanjing, China is evaluated by the method. The environmental quality comprehensive indices (EQCI) of sediment in 1996-2000 and 2001-2005 are 4.52 and 3.32, indicating that sediment contaminations decrease in the decade. Such results in accord with the fact bring the Qinhuai River under comprehensive control. However by the classical AHP method the EQCI of sediment may indicate that sediment contamination increases from 1996 to 2005. The judgment difference by experts leads to the uncertainty of assessment result. Therefore, the improved AHP method can avoid arbitrariness of subjective judgment and reflect objectively the changes of factors contribution to environment pollution in different periods or regions.School of Geographic and Oceanographic Sciences