The researchers studied water quality in Poyang Lake, China, from 2009 to 2012. They developed a model called IFVE to evaluate water quality variations. Results showed that chlorophyll-a concentration and Secchi depth varied significantly among sampling sites, while all water quality parameters varied throughout the seasons. The IFVE model effectively assessed water quality and considered the impact of poor indices. Human activities and lake topography directly affected water quality, with seasonal variations influenced by hydrology and sewage discharge.