Improved comprehensive index method and its application to evaluation of source water quality in Shanghai
改良综合指数法及其在上海市水源水质评价中的应用

In order to establish an improved comprehensive index method applicable to water quality assessment of surface source within a centralized drinking water supply system, several comprehensive index methods of index-converted, weighted average, minimum operator and Nemerow index were selected. For the weighted average approach, weighting coefficients of different index categories based on health impacts of the indices detected were determined using the expert consultant method. Evaluation results of source water quality for Shanghai in 2007 by this improved method showed that the overall quality of source water conformed to the relevant national standard; nevertheless organic pollution of source water could not be ignored. Further analysis indicated that the Yangtze River was the best source choice for Shanghai; source water quality of suburban water factories was inferior to that of their urban counterparts; source water quality of municipal-level water factories was the best; and source water quality in the first quarter of 2007 was comparatively inferior. The improved comprehensive index method developed in this paper has the merit of simplicity, rationality and powerful operability, and thus is applicable to the evaluation of source water quality in other cities.