Research On Extracting The Information Of Water System And Mapping Changes Based On TM

Water system is an important part of Basin. The information of water system (such as the classification of watercourse, the area of catchments, and so on) is the basic data which is used to the hydrological models. The RS methods which are used to gain the revising data of extracting water system by DEM can improve the level of automatically getting the revising data and update the DEM revising data in time. The method of extracting water system in basin and the research of change cartography have important meaning to analyze and manage the basin ecosystem.In this paper, taking the water system of Lou River for an example, an automatic method of extracting water system is put forward based on RS image. This method can not only satisfy the accuracy of revising data, but also offset the flaw of optical interpretation. Furthermore, to extract main water system automatically increases the interpretation speed and reduces the participation of human being. It has advantage to implement large area dynamic supervision. The main contents and results of this paper are as following:1. The modification of atmosphere is a problem in the pretreatment. 6s model is adopted to carry out atmospheric modification and Lambert reflected model is applied to eliminate the influence caused by terrain. According to modifications, the water system can be extracted better.2. In reference to traditional extract method, the main water system is classified from the image automatically combined with geographical and morphological knowledge. The main water system in Lou River basin is got by water index and morphological knowledge and the DEM revising data can be acquired. In order to acquire high accuracy in part area, the threshold of water index is amplified and more geographical knowledge is used to interpret the images.3. The main water system is used to modify the water system derived from DEM. Meanwhile,the changes are mapped by the software. Through the map, it could be found that the urban main watercourse position has been changed, which were affected by many factors, such as man-made, nature, flood season and so on.