Quantitative Assessment of Water Quality Improvement by Reducing External Loadings at Lake Erhai, Southwest China

• Published in: International journal of environmental research and public health Vol. 20; no. 6; p. 5038
• Main Authors: Gong, Falu, Luo, Liancong, Li, Huiyun, Chen, Lan, Zhang, Rufeng, Wu, Guizhu, Zhang, Jian, Shi, Weiqiang, Zhang, Fan, Zhang, Hao, Sun, Ting
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.03.2023; MDPI
• Subjects: Analysis; Aquatic resources; China; Creeks & streams; Ecological models; Environmental Monitoring - methods; Environmental quality; Eutrophication; Evaluation; Lakes; Nitrogen; Nitrogen - analysis; Nutrients; Phosphorus; Phosphorus - analysis; Pollutants; Pollution; Pollution control; Pollution sources; Quality assessment; Quality control; Quality Improvement; Quality standards; Rain; River ecology; Rivers; Shipments data; Surface water; Water inflow; Water levels; Water Pollutants, Chemical - analysis; Water Quality; Water quality assessments; China; Lake Erhai; Yunnan China; Taihu Lake; Lake Erhai; water quality; DYRESM–CAEDYM; external loadings
• ISSN: 1660-4601; 1661-7827; 1660-4601
• DOI: 10.3390/ijerph20065038

To quantitatively evaluate the effects on water quality improvement caused by reducing external loadings entering Lake Erhai through inflow rivers, a one-dimensional hydrodynamic and ecological model (DYRESM-CAEDYM) was set up to simulate the water quality and water level variations. The calibrated and validated model was used to conduct six scenarios for evaluating the water quality responses to different amounts of external loading reduction at Lake Erhai. The results show (1) the total nitrogen (TN) concentration of Lake Erhai will be higher than 0.5 mg/L without any watershed pollution control during April-November 2025, which cannot meet Grade II standard of the China Surface Water Environmental Quality Standards (GB3838-2002). (2) External loading reductions can significantly reduce the concentrations of nutrients and Chla at Lake Erhai. The effects of water quality improvement will be proportional to the reduction rate of external loading reductions. (3) Internal release might be an important source of pollution It needs to be seriously considered as well as external loading for mitigating the eutrophication at Lake Erhai in the future.