武汉湖泊富营养化遥感调查与评价

利用武汉东湖各子湖多年可靠的地面监测资料和1999年9月Landsat-7的TM各波段的卫星遥感数据,建立了各子湖的营养状态指数与TMb5图像上的灰度值之间的线性关系模型,并运用该模型对武汉各湖泊进行富营养化评价。同时基于地面监测资料,用日本学者相崎守弘提出的修正富营养化指数法对武汉主要湖泊的富营养化程度进行评价。两种方法评价结果都显示,武汉大多数湖泊呈富营养化状态,一些湖泊已接近甚至达到极富营养化。在用两种方法同时评价的十个湖泊中,有四个湖泊的评价结果完全一致,其余的六个湖泊富营养化程度只相差一个级别。两种方法评价结果存在差异,可能有以下三个原因;（1）遥感方法反映了是图像所在时段的某一个区域上的平均值,营养化指数法反映的是若干个采样站的年平均值;（2）TM图像的获取时间比地面监测的时间晚;（3）遥感影像可能受到云、泥沙等悬浮物、高等水生植物以及湖泊水深等的影响。遥感评价结果与地面监测结果基本一致,利用遥感进行湖泊水体富营养化监测价是可行的,有效的,利用该方法可进行大范围的湖泊富营养化调查评价。

INVESTIGATION AND EVALUATION OF EUTROPHICATION OF LAKES IN WUHAN AREA BY REMOTE SENSING

Through the analysis of the Thematic Mapper (TM) images in September,1999, and reliable monitoring data for many years of several small lakes of Donghu Lake in Wuhan area, the authors discovered a good linear relation ship between the values of grey degree (GD) abstracted from TM b5 images and eutrophication indexes of the lakes. The authors investigated and evaluated all the main lakes in Wuhan area according to the models. At the same time, based on the \$sit tiu\$ monitoring data they also evaluated the eutrophication degree of lakes in Wuhan area by an other method "Amended Atrophic Indices" which was brought forward by Japanese scholar Morikiro Aizaki.The evaluated results by both methods show that most lakes are eutrophic, and some of them have even reached hypereutrophic states. Among ten lakes evaluated simultaneously by the two methods, there are four lakes whose evaluated results are identical, and there are six lakes whose evaluated results vary by one level. There are three reasons for the difference between the results of the two methods. First, remote sensing technology reflects the average values of a certain area corresponded with TM images in a certain period, but "Amended Atrophic Indices" reflects the annual average values of the monitoring spots. Second, the time of TM images is later than that of \$sit tiu\$ monitoring data. And third, TM images are affected by cloud, water depth, suspension, such as sand, hyper hydrophytes, etc. In a word, the result by remote sensing is almost agreed with the monitoring data. It means that remote sensing technology is feasible and effective to monitor and evaluate the eutrophication of lakes in Wuhan area and it can also be used to investigate and evaluate lake eutrophication in larger area.