Contrastive Study on Comprehensive Evaluation of Water Quality in Taihu Based on Various Methods

Water pollution is one of the worst problems of water environment in Taihu Basin. To evaluate the water quality exactly and reasonably is vital to grasp the characteristic of water pollution and water environmental management. Single index was used to evaluate the pollution level of single element in typical sections. The original and improved comprehensive index and grey incidence analysis were used to evaluate the integrated water quality from 2004 to 2013. The results showed that the pollution level of east and southeast in Taihu Basin was more serious and the main pollutant was NH3-N, which was in accord with the situation of eutrophication, so the leading management was to reduce the water eutrophication. There were some differences among the results of different water quality evaluation methods. The results of original and improved comprehensive index were more accurate than grey incidence analysis, and the trend of the results calculated by original comprehensive index and grey incidence analysis preferred to the lower level, and the improved comprehensive index which combined with the influence of the worst pollutant to the integrated water quality preferred to the higher level, overcoming the error caused by the algebraic average of single index and reflecting the pollution of watershed veritably. Overall, the improved comprehensive index was recommended to evaluate the water quality.