Water Quality Characterization of the Siling Reservoir (Zhejiang, China) Using Water Quality Index

Monitoring and protection of drinking source water is important for safe drinking water provision on sustainable basis. The Siling reservoir is a major drinking water source for the inhabitants of Yuhang County, Hangzhou City, Zhejiang Province, China. In this study, water quality index (WQI) was verified to calculate scores based on water characteristics data from September 2011 to September 2012. WQI (considering ten parameters) and a minimal water quality index (WQImin) (considering five parameters: dissolved oxygen (DO), electrical conductivity, turbidity, water temperature and pH) were investigated using an online water quality monitoring system. Statistical analysis techniques: correlation analysis and redundancy analysis were employed to analyse the obtained data. The results showed good water quality in the Siling reservoir during autumn and winter. However, a decreased trend in water quality was observed during spring and summer seasons. WQImir, illustrates similar trend to WQI with a better R2 value of 0.99, with a minimum cost and could be useful for the intervallic routine monitoring program. Higher positive correlation between WQI and DO was observed during winter season. Moreover, the results further indicated the risk of algal blooms in the reservoir water; which reflected the effects of climatic condition on reservoir water quality. This study suggested that the resulting WQI provides valuable information on developing, monitoring and understanding surface source water quality for the decision makers and reservoir management.