Spatio-temporal Distribution Characteristics of Water Quality in Miju River and Erhai Lake

In the research related to the water resources management and prevention of pollution, it is of great practical significance to analyze the spatial and temporal distribution characteristics of the water quality. The present work deals with the study on the actual water quality monitoring data obtained from the Miju River monitoring sections in the Erhai Lake during 2011-2016. Six water quality indicators were selected for investigation using the comprehensive pollution index method and the principal component analysis method, in order to analyze the spatial and temporal distribution characteristics of water quality in the Miju River Basin. The results of the comprehensive pollution index method showed that the water quality of the Miju River has not changed much in the past 6 years, and the water body has only been slightly polluted. Additionally, the water quality of the Jiangweiqiao section was slightly inferior to that of the Yinqiaocun section. Principal component analysis method showed that the nitrogen pollution was the dominant factor in the wet season, followed by phosphorus, pH and dissolved oxygen. In the normal season, the dissolved oxygen and pH of the water were the main factors, followed by phosphorus and ammonia nitrogen. In the dry season, the dissolved oxygen, ammonia nitrogen and organic matter pollution were the main influencing factors followed by phosphorus and pH. The water quality of the Miju River in the past 3 years was slightly worse than that in the initial 3 years, and the overall performance of the water quality of the Miju River was relatively best during the dry season followed by the normal season, while the water quality was worst during the wet season. Furthermore, the water quality variation trends of Yinqiaocun and the Jiangweiqiao sections were observed to be similar.