Study on channel islands in Ma-wu-tong Section of Yangtze River based on remote sensing image

There are many accumulation channel islands in Ma-wu-tong Section of Yangtze River, and the area of channel islands change rapidly. We choose eight channel islands and study their changes on TM(Thematic Map) which date are 1979s, 1990s, 2001s, 2006s and 2009s. We determined the spectrum of typical objects in channel islands by ISI921VF-256T Field Spectroradiometer, combined the right bands, and interpreted the images by geometric correction, subset images, binarization processing, convolution, clump. Through the interpreter, we draw the changes of 8 channel islands and we got: (1)TM remote sensing data could be used to achieve channel islands change information quickly and accurately; (2)The 8 channel islands were extended continually during past 30 years. The speed of extended was not averagely, and reducing water or decreasing the sediment-carrying capacity maybe result in that phenomenon; (3)Evolution of channel islands were constraints by natural factors and human factors. A direct result of natural factors was ablation or siltation of channel islands, and human factors change would result in the change of external substances, which was composition of channel islands.