| Inland lake is a important water resources. As the global water resources shortage, thelake protection and pollution control work has become particularly important. The mainpollutions of water are eutrophication of lakes and huge outbreaks of algae in fresh waterlake. In Inner Mongolia, the Wuliangsuhai is also facing the same problem. In recent years,the degree of eutrophication of lakes was increased, leading to algae outbreak of"Huangtai" many times. With the Huangtai outbreak of large area, the lake wild birds’ andfish’s environment are serious polluted, and the lake and the surrounding areas ofecological balance are broken, and the production and living of the people to thesurrounding areas are affected. Therefore the monitoring and prevention of Huangtai hasbecome the important content, and provides the powerful basis to the local government forthe timely and effective measures to deal with Huangtai. Regular monitoring istime-consuming, laborious and limitations. But using the Remote Sensing Technology canquickly and timely response the lakes overall state. It has many advantages, such as theshort time, the wide range and the low cost. So it is suitable for long-term dynamicmonitoring of lake. In this thesis, the main contents are as follows:In the first chapter, the status of the research object—Wuliangsuhai in the domesticfreshwater resources and the serious pollution problem of Huangtai were introduced. Inaddition, the research progress on lake algae blooms monitoring at home and abroad weregiven. The methods and researches of using the Remote Sensing Technology to monitor thelake water quality and algae, and inversion of chlorophyll’s concentration are summarized.In the second chapter, selecting the MODIS and TM images as the data source ofremote sensing monitoring, referring to the conventional method of preprocessing remotesensing image, combining with the characteristics of image itself and the research object,we can choose the appropriate pretreatment method to image processing for the MODISand TM image.In the third chapter, based on the TM data, the important index—the concentration ofchlorophyll A of lake’s algae is inversed using the remote sensing. After analyzed themeasured concentration of chlorophyll A and TM band’s data, combined with the characteristics of Wuliangsuhai, the partition inversion method can be proposed. The highcorrelation between chlorophyll a concentration and band combination (TM1+TM2+TM4/TM3) is found. Thus the inversion model is built. We can get the distribution ofchlorophyll a concentration on July23,2009. The result show that chlorophyll aconcentration gradually reduced from north to south, and that the west is low in status.Thus the key monitoring area can be built, and then the basis is provided for the huangtaiearly warning.In the forth chapter, the spectrum characteristics of the different features in theMODIS data of visible light and infrared light are analyzed. Combining with the feature ofhuangtai, selecting blue band and red band as different wavelengths, huangtai’sinformation is extracted using ratio algorithm, and the huangtai’s rank are divided. FromMay2008to October, according to the results of huangtai’s information, it can be showedthat Huangtai breake out in May. The area gradually increased in June and July, andreduced in August. Huangtai almost disappeared in early October.In the fifth chapter, the research results of this thesis are summarized and discussed,and the outlook for further work is pointed out. |
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