Carrying Capacity of Water Environment and the Associated Optimization of Socioeconomic Structure of Yangzong Lake Basin, China

Yangzong Lake is the third largest deep-water plateau lake in Yunnan, China. Rapid socioeconomic development of the basin has resulted in pollution of water environment. This study aimed to identify the carrying capacity of water environment and to conduct the associated optimization of socioeconomic development. The results of this study showed that: (1) The carrying capacities of tributary rivers were small in relation to that of the lake. The maximum allowable annual loads of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP) into the main rivers of the basin were 449.37, 24.73, and 5.38 tons, respectively. (2) Under the planning scenario, COD and NH3-N loads remain the primary constraints on economic and social development in the watershed. (3) In further optimizing the structure of the plantation industry, focusing on strengthening the collection and treatment capacity of rural domestic sewage, the watershed can achieve high-quality development of the tourism industry. The tourism output value in 2025 and 2035 can carry up to 20.28 billion CNY (growth rate: around 15.44%) and 76.80 billion CNY (growth rate: around 14.64%), respectively. This study can provide basic support for the future economic and social development of the watershed for decision-makers.