Seasonal Variation of Water Color at 30m Spatial Resolution in 42 Urban Lakes

Eutrophication has been a serious problem in China’s urban lakes. In this study, to monitor 42 lakes trophic state in Wuhan city, a Forel-Ule index (FUI) method based on Landsat 8 OLI data was proposed among different seasons. The result shown that the FUI calculated from Landsat 8 OLI reflectance spectral (Rrs) can substantially represent the lakes TSI, with accuracy of 79.37% for in situ experiment TSI dataset. And the TSI in urban lakes can be divided into 3 categories by a decision tree (oligotrophic, FUI 1-6; mesotrophic, FUI 7-9; trophic, FUI 10-21). Seasonal dynamics show that the trophic state of 42 lakes in summer is significant higher than other seasons, while 99.65% lakes are under the state of trophic. And the order of average FUI is summer (19) > spring (18) > fall (11) > winter (10). Our results can serve as an example for other lakes lie in Yangtze River basin, and support the formulation of effective strategies to reduce seasonal eutrophication.