Monitoring Of Water Eutrophication Status For Fresh Water Lakes By MODIS Remote Sensing Image

China has been recognized as a "water shortage" country by the United Nations, and its water environment is also worrisome: the emissions of pollutants far exceeds the capacity of the water environment, the rivers and lakes are polluted generally, about 75% of the lakes are in different degree of Eutrophication all over the country, the other water problems are such as lacking of using water, the pricking up trend of the water environment deterioration and so on. Therefore, it is extremely urgent thus we should determine the scope and degree of the polluted water area so as to take effective treatment measures to fresh water lakes.The article takes emerging remote sensing technology and the remote sensing data which are received by MODIS sensor in Terra satellite to monitor the water eutrophication status of the fresh water lakes in real time.There are few researches on water eutrophication status of fresh water lakes based on MODIS data at home and abroad nowadays, and the aim of this article is just about to establish and improve the water extraction models and methods which based on MODIS data by using the spatial information technology firstly, then we can take on further researching on the fresh water pollution status of the Dongting Lake.I introduce the pre-processing methods and some characters of the MODIS data from the remote sensing's basic keysotones, including electromagnetic radiation, the spectrum signature of the typical ground objects (mostly about the water spectrum signature which contains different volume of chlorophyll-a). Also explain the definition, formation cause and harmness of the water eutrophication, then put forward the water extraction models such as index model, supervise classification model and decision tree model based on MODIS remote sensing data, at last I will take MNDWI index model to catch on water extraction operation from comparison. The key point of this paper is to explain and apply the LSMM and WST model to monitor the relative consistency of chlorophyll-a, elicit the water eutrophication status of the Dongting Lake, and then using the historical article to check the validity of the monitoring results, finally extending to apply the models to Taihu Lake to judge their universality.For the MODIS data which used in the LSMM models and WST models of this article are free and the MODIS sensor is an optical sensing instrument which"oneness of the image and spectrum", it has medium spatial resolution and high time resolution, so the models are very useful for the environmental protection department to monitor the water quality, also providing a certain theoretical basises for government to take on the water environment management.