The Application Of RS Technique On Studying Influence Factors Of The Riverway Evolvement In Anhui Reach Of Yangtze River

With large valley, developed economy, complex geological and geographical condition, abundant waterpower and power resources, and longest shores, Yangtze River is the biggest river in China and is regarded as a important and difficult hot region in the geology, geography, hydrology and engineering realm. The part of river in Anhui stands in the lower of the river and is diverged river. There are a lot of nodes and complex river course. Since 1950s, riverbank collapsed, river course changed, inlets and outlets of the river were silted up and the flood pile up one after another. With the operation of Three Gorge Project, riverway will be more complex. So researching the characteristic and the evolution of Yangtze River riverway, understanding the influences on the evolution of Yangtze River course, further to studying the evolution mechanism of the river, are important in science research and actual application.The influence factors of the river course evolution include climate, hydrology, geology, geological tectonic, Colioli Force, and human activity, and their functions are different, and they are more and more important in the last 50 years, especially water current containing sand, and human activity. However, people studied the riverway mainly by field survey and landform map contrast before. Because of the limits of man's field view and complexity of field survey route, it is a difficult bottle neck for people to make synthetical analysis on geological structure, Yangtze river shoal, floodplain, terrace, and microcosmic suspended load on macroscopical scale. So the results of the evolvement of the riverway concluded by above mentioned methods are more or less different from its actual evolvement, and the estimate is not quantitative.On the basis of Remote Sensing technique's good characteristic with large-area, multi-time, multi-photograph variety, manifold abundant spectral information and high ground resolution, the fault tectonics frame,river geomorphy (such as terrace, floodplain, shoal, etc) and suspended load, etc. were explained after analyzed the fault tectonics, river geomorphy, characteristic in the TM image by gray bar statistics, primary component analyses,TM741 image integration, line convolve enhancement and model recognition etc. especially 9 piece of fault tectonics were explained in this thesis, in succession, the impacts of the factors severally were analyzed.That is, the evolvement of Anhui reach of Yangtze River was influenced by many kinds of factors: geomorphy is the elementary factor, and climate influence water and sand offered by river basin. Structural movement of earth crust from north to south cause the riverway move from north to south. Northeast faults control the spread of the Anhui riverway, and eastwest faults resulted in the widening of the river and the occurrence of nodes, then the stream raised and the riverway turn into goose pattern braided river. Northwest faults and Northsouth faults influence the evolvement of partial riverway, for example, the northwest Lujiang-zhongming fault influence the evolvement of Tongning shoals, and the northsouth faults passing throughZongyang-Digang make the riverway's direction from North-east to North-south. In a word, the geological structure controls the terrain and water system radically, then control the river basin pattern, which is reflected on condition of the changed coming water, sands and its boundary. That's to say, the evolvement of Anhui riverway is adapted to the geological structure. In addition, the microcosmic stream, especially suspended load (mainly suspended soils and sands) reflected on the characteristic of transported sands' streams, and always silt up and form shoal in the place where the stream velocity is lower and river steam return easy. And prepare for the being and coming riverway evolvement.Simultaneously, based on the contrastive analysis of data on the river, we studied the evolvement of the Anhui riverway, in historical epoch and especially in the past 50 years. Characteristic of the evo...