基于GF-1影像的洞庭湖区水体水质遥感监测

湖泊水质监测是有效开展湖泊水环境综合管理与水污染防治实施的基础,也是湖泊藻华风险评估与生态安全建设的重要依据。本文基于GF-1号影像对2014-2016年洞庭湖水体的叶绿素a浓度、悬浮物浓度和透明度展开遥感监测,结果表明：叶绿素a主要集中在水流速度较慢的安乐湖、大小西湖和东洞庭湖西部地区,其他区域水体扰动力大,叶绿素含量a较低。透明度从北到南递增,与悬浮物浓度的分布趋势相反,符合常规监测规律。东洞庭湖水质较南洞庭湖和西洞庭湖差,水污染程度处于全湖最高水平。GF-1数据可精确反映叶绿素a浓度、悬浮物浓度和透明度指数的空间变化规律,也为后续高分遥感影像湖泊水质监测的应用研究提供了重要参考。

Monitoring water quality of Dongting Lake region based on GF-1 image

Lake water quality monitoring is the foundation for the effective implementation of comprehensive management of lake water environment as well as water pollution prevention and control. Moreover, the dynamic monitoring of water quality can provide an important basis for the assessment of the risk of algal bloom in lakes and the ecological safety construction in the lake area. Dongting Lake is the second largest freshwater lake in China, the acceleration industrialization and urbanization had caused the lake water pollution to be more and more serious in recent years. Many studies were focused on the traditional water quality monitoring method that rely on chemical analysis after water sample collection, but paid less attention to the remote sensing technique due to the shortages of aerospace imagery. In this paper, the GF-1 image during the period 2014-2016 were collected based on the high resolution earth observation system Hunan Data and Application Center, and the inversion of water quality parameters of Dongting Lake was carried out including chlorophyll-a concentration, suspended matter concentration and transparency. The water boundary of Dongting Lake was extracted by the normalized water index (NDWI), and water quality parameters were quantitatively retrieved by the remote sensing model. The results show that the chlorophyll-a was mainly concentrated in the Anle Lake, Daxiao West Lake and the western part of East Dongting Lake, where the flow speed is slow, the chlorophyll-a content in other parts of Dongting Lake is relatively low due to water disturbance. The transparency of water quality is relatively high in the tributaries, then decreases from south to north and reaches the peak in the Yangtze River Estuary. There is a negative correlation of spatial distribution between transparency and suspended matter concentration as a whole, which is consistent with the routine monitoring rule. The water quality of the East Dongting Lake is much worse than that of the southern Dongting Lake and the West Dongting Lake. The water pollution of East Dongting Lake is at the highest level of the whole lake, which is closely related to human activities, causing a large amount of pollutants, agriculture and forestry chemical fertilizer being discharged into the East Dongting Lake. The GF-1 PMS imagery can accurately reflect the spatial variation of chlorophyll a concentration, suspended solids concentration and transparency index, and this study is expected to provide an important reference for the study of theory, method and application of inland lake water quality monitoring based on high-resolution remote sensing images.