The Analysis and Prediction of the Water Quality of Lashi Lake in Lijiang

This paper analyzed the change of water quality of Lashi Lake in Lijiang, the status index of eutrophication and the pollution index of Nemerow were analyzed by Spearman correlation from 2018 to 2021, the change trend of monitoring items, the pollution index of single factor and the principal component were analyzed. The reason of p H value exceeding the national standard was analyzed. The traditional time series model was used to predict the sea water quality in 2022 in Lashi Lake. It provided protection ideas and methods for the lake. The results showed that the pollution index of Nemerow in Lashi Lake increased significantly, the change trend of nutritional state index was not significant, and the whole water quality became worse. The results of principal component analysis showed that the main items affecting the water quality of the Lake were related to the oxygen-consuming substance, dissolved oxygen concentration, acidity, alkalinity, nitrogen and phosphorus cycling in the Lake. The pH value in 2022 was expected to exceed the standard in August and September, and the annual average in 2022 would meet the category III standard.