综合遥感与地面观测的巢湖水体富营养化评价

提出一种将地面观测数据空间插值与遥感反演结合的湖泊富营养化评价方法与业务化运行模式。对叶绿素a等可反演参数利用遥感影像反演,并利用实测值校正获得高精度反演结果;对总磷等不易反演参数采用空间插值获取全湖区数据,采用综合营养指数法对巢湖富营养化状态进行反演,获得2015年5月12日巢湖富营养化状态空间分布情况。结果表明,巢湖全湖为轻度和中度富营养化状态,呈现出西半湖高于东半湖的总体空间分布趋势。结合相关数据对巢湖富营养化成因进行推断,认为南淝河等上游河流各类营养物质输入量较大是造成西半湖北部富营养化严重的主要成因;西南部杭埠河等河流氮磷输入量较大,但其他营养物质输入较少,使得该区域总体呈现出富营养化程度偏低的现象。

Eutrophication Assessment of Chaohu Lake using Remote Sensing and In-Situ Data

The monitoring and estimation of lake eutrophication is an important issue in China, which is one of the regions with the most serious eutrophication problem in the world. However, the current evaluation methods of lake eutrophication are restricted to separately using either the mean water quality of a few water samples or remote sensing retrieval of limited water quality parameters with low accuracy. This study proposed a new evaluation method and vocational operation for lake eutrophication, taking advantage of the interpolation of field observation and remote sensing retrieval. Parameters suitable for remote sensing retrieval, such as chlorophyll-a,were obtained by remote sensing inversion, and then calibrated with in-situ data for higher precision. Parameters difficult for remote sensing retrieval, such as phosphorus, were spatially interpolated from in-situ data for the whole lake area. The lake eutrophication status was estimated with all these parameters using the comprehensive Trophic Level Index method (TLI). In the end, we obtained the eutrophication status map of Chaohu Lake on May 12, 2015. The results indicated a nutrition level between lightly and medium eutrophicated in the whole lake with a spatial pattern of higher trophic status index in the western area than the eastern area. The causes of europhication in Chaohu Lake were inferred considering relative data such as the river system and the image data. On one hand, the huge amount of nutrient input from the upstream rivers such as Nanfei River was probably the main reason for the most serious eutrophication problem in the north-western part of the lake. On the other hand, the TLI value was lowest in the southwestern part of the lake probably due to the large input of nitrogen and phosphorus while little input of other nutrients from the southwestern rivers such as Hangbu River.