基于FUI模型的柬埔寨洞里萨湖水体颜色研究

洞里萨湖(Tonle Sap Lake)是东南亚最大的淡水湖泊，研究其水体颜色的时空分布能够为评估洞里萨湖水质综合状态的变化提供重要信息.该研究使用2000年－2018年间中分辨率成像光谱仪MODIS的地表反射率数据，在水体颜色指数FUI模型的基础上，定量分析了洞里萨湖色调角的年际变化和年内差异、色调角与水面面积的关系、水体颜色变化率的空间分布特征、以及富营养化状态的逐年变化.结果表明：1) 洞里萨湖的水体颜色在19年间呈现由黄向绿的转变，但不显著，2014年－2016年的年内差异明显减小并出现了短暂的稳定；2) 不同月份色调角的逐年变化趋势存在明显差异，有8个月的色调角与面积存在显著的相关关系，最强的正/负相关关系分别出现在雨季6月(R＝0.72)和旱季12月(R＝－0.86)；3) 在雨季、旱季的代表月份6月、12月，色调角年际变化率的空间分布差异较大，12月的逐年变化幅度明显高于6月，但变化趋势呈现显著性的区域较少；4) 19年间，洞里萨湖的营养化状态在雨季6月以“富营养”状态为主，在旱季12月存在明显差异.研究结果量化了近20年来洞里萨湖水体颜色或水质综合状态、富营养化程度的演变程度及空间分布，为该湖泊的水质监测与治理提供基础数据支持.

Study on water color of Tonle Sap Lake in Cambodia based on FUI model

Tonle Sap Lake is the largest freshwater lake in Southeast Asia. Study on the spatial-temporal distribution of its water color could provide important information for assessing the change of comprehensive states of water quality. This paper used MODIS surface reflectance products from 2000 to 2018. Based on Forel-Ule Index (FUI) model， the interannual and monthly variation of the hue angle and its relationship with water surface area was quantitatively analyzed. The spatial distribution of water color change rate as well as the changes of trophic states were also characterized. The results showed that firstly the water color of Tonle Sap Lake changed slightly from yellow to green in 19 years， and the monthly variance decreased from 2014 to 2016. Secondly， the monthly discrepancy of hue angle was distinct. There was a significant correlation between the hue angle and area of Tonle Sap lake for 8 months. The most positive and negative correlation occurred in June of rainy season (R＝0.72) and December of dry season (R＝－0.86). Thirdly in the representative months of rainy season and dry season， the spatial distribution of interannual change rate of hue angle was quite different. The change range in December was higher than that in June， and few regions were evaluated as significant in both months. Lastly， the interannual trophic state of Tonle Sap Lake in December was different from that in June in which “eutrophication” was dominant. Concisely， this study provided basic data support for water quality monitoring and management of Tonle Sap Lake on the basis of trophic state assessment and the quantification of water color and its spatial-temporal distribution.