Nutrient zoning of Poyang Lake based on aquatic eco-environment indices

Nutrient zoning is an important basis for the monitoring, evaluation, protection and management in lakes. In comparison to other freshwater lakes, Poyang Lake contains better water quality as the biggest fresh-water lake in China. The eco-environmental indicators change by spatial distributions, which is significant for the nutrient zoning of Poyang Lake. Through the nutrient zoning indicator analysis, a standard index system of Poyang Lake was set up containing five indicators: transparency, chla, TN, TP, and COD. By using hierarchical cluster analysis combined with administrative boundaries and aquatic ecological zoning steps, principles, and methods, Poyang Lake was divided into six zonings: Rujiangshuidao Region, West Lake Region, North Lake Region, South Lake Region, Northeast Lake Region, and Southeast Lake Region. The decreasing order of trophic level index in every individual region is from North Lake Region, Northeast Lake Region, Southeast Lake Region, South Lake Region, West Lake Region, to Ruijiangshuidao Region. Nutrient zoning could provide scientific support for eutrophication research, eco-environment protection and management in Poyang Lake.