Spatiotemporal Variations in the Water Quality of Qionghai Lake, Yunnan–Guizhou Plateau, China

Although Qionghai Lake is one of the 11 large and medium-sized lakes (lake area > 25 km2) in Yunnan–Guizhou Plateau (YGP), there has been little research on its water quality, especially over long term. Herein, meteorological, hydrologic, trophic, biochemical indices were investigated 2011–2020 period to explore spatiotemporal variations quality Lake. The results showed that CCME-WQI value for ranked between marginal fair during 2011–2020, before 2017 was worse than after 2017, western part eastern part. Total nitrogen total phosphorus 0.39–0.51 0.019–0.027 mg/L respectively, main pollution factors In addition, at mesotrophic level, but chlorophyll trophic state levels (TLI) increased year by year, higher area. Increased anthropogenic activities (industrialization, urbanization, agricultural intensification, etc.) reasons poor while, effective government environmental restoration management measures improved quality. Moreover, difference land-use types within watershed reason spatial heterogeneity Potassium permanganate index (CODMn) ammonia content (NH3-N) not very high, both seasonal variations. Water transparency (SD) reduced sediment input algal biomass, while dissolved oxygen (DO) decreased due thermal stratification. This study expected provide a theoretical reference understanding changes protection YGP.