YANG Hua1，LI Yanhua2，WEN Hongxing1，LI Hongyan1
1.Dali Branch of Yunnan hydrology and Water Resources Bureau，Dali Yunnan 671000；
2.Yunnan hydrology and Water Resources Bureau，Kunming Yunnan 650106
Objectives of the study
The Erhai Lake stands as the second largest freshwater lake in Yunnan Province and one of the nine plateau lakes in Yunnan. It’s not only the most integral scenic spot in Dali, but also the main source of water for the living and production of the surrounding people. The Erhai Lake is a typical inland fault-depressed lake, which has certain closed and semiclosed characteristics. Over the past 20 years, with the surging economic development and population growth in the lake area, human exploitation of its natural resources has intensified, resulting in accelerated eutrophication, declining water quality, and gradually deteriorating ecological environment. It’s part of the Cangshan Erhai Lake Nature Reserve, and the water quality protection target is Class Ⅱ. It’s suggested by the monitoring data in 2017 that the water quality of the Erhai Lake is generally in Class Ⅲ, and the nutrient level of the lake is at the medium nutritional level. Given the status quo of the ecological environment of the Erhai Lake, it’s of vital importance to build a health assessment system suitable for the Erhai Lake, which can provide a scientific basis for the protection and management of the Erhai Lake, and can also serve as a reference for the health assessment of other plateau lakes in Yunnan Province.