| The Beijing-Hangzhou Grand Canal is one of the longest man-made rivers all over the world, had a history of about 2500 years. In 2006, the authority of China had decided to apply The Beijing-Hangzhou Grand Canal for world cultural heritage, so the canal was regarded as an important and difficult hot region in history, cultural relic, geographical, communication, hydrology and engineering realm. So researching the characteristic and the evolution of rivers in Qingkou Region, which one of important part in The Grand Canal, further to studying the evolution mechanism of the river, are important in science research.In the past, people studied the riverway mainly by field survey and landform map contrast before. Because of the limits of human's field view and complexity of field survey route, the analyzed results of evolvement of the riverway concluded by above mentioned methods were different from its actual evolvement more or less. Remote Sensing technique has a good characteristic of large-scale, multi-temporal, abundant spectral information and suitable for research on evolution of river that span long period and large scale. This paper studies in the following areas:1, Factors that affect the evolution of the river and the application of remote sensing technology were analyzed. The development of research on evolution of river was analyzed; methods and achievement about research on application of space information technology in the evolution of the river as well. On this basis, the content and meaning of this research was demonstrated;2, Information interpretation. On the basis of literature research, ancient map in Qing Dynasty was collected; combine with GPS measurement data, the river information in Qingkou Region was interpreted in 4 period of Qing Dynasty;3, Change detection and information extraction. In the detection of changes in the river, spectral variation method and the composite method were adopted and compared to identify a suitable method; in the extraction, it was not available to find a common method that suitable for all types of data, 4 methods were used in this paper as follow: relationship between spectrum method, water index method, vegetation index method and vector-based human-computer interaction method, to find an more convenient, fast and accurate method for extraction;4, Research on Evolution process of the river in Qingkou Region. After interpretation and extraction, the spatial distribution of the river and branch in Qing Dynasty and modern times was obtain. After that, river information that interpreted and extracted was overlay in the same geography coordinate, to analysis the evolution process of the river. On this basis, the impact factors were explored further.The main conclusions of the paper made the following points:1. Dramatic changes had taken place in Qingkou Region in the past over 300 years. The evolution of the rivers in region seems repetitive. Two large-scale changes have taken place after the founding of China: one for period between 1954 and 1989; another for period between 2000 and 2006, with a area of 79.3 percent. In recent years, the river has becoming stabilized, no great changes fundamentally;2. the composite method was found to be more effective than the spectral variation method when detecting changes, the former method has higher precision, change information was obvious and easy to be interpreted; when extracting river information, relationship between spectrum method was more effective than other methods, for river information and spatial distribution were reflected best, even small water body;3. The evolution of the river was influenced by natural factors and human factors at the same time. Natural factors having more influence than human factors in Qing Dynasty, however, human factors become dominant factors in the evolution of modern time; changes in the river have made the river course steadier gradually. |
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