Study of multi-dimensional water quality safety evaluation method: taking Taihu Lake as an example

Based on the characteristics of water pollution of Taihu Lake, the indicators including water quality, eutrophication, water bloom occurrence and health risk were screened, and a multi-dimensional water quality safety evaluation index system consisting of 4 secondary indicators and 21 tertiary indicators was constructed. Analytic Hierarchy Process (AHP) method was applied to determine the weight of the indicators. The survey data of Taihu Lake in 2012 was used to evaluate the water quality safety grade with the water quality safety index. The results showed that the overall water quality safety of Taihu Lake was only qualified in 2012. The water quality safety grade in the eastern district of lake was medium, while the water quality safety grades in other districts of the lake were qualified. The water quality safety status of Zhushan Lake and Northwest District was the worst, and the water quality safety index was 50.78 and 52.45, respectively. Based on the analysis of the assessment results, eutrophication level and water bloom condition were found to be the main factors affecting the water quality safety of Taihu Lake.