长江口九段沙潮沟系统分维研究

Fractal dimensions of tidal channels at Jiuduan Shaol in the Yangtze River Estuary

以长江口九段沙为研究区,采用2013年8月13日的Landsat-8遥感全色波段得到的九段沙潮沟分布图,利用Horton-Strahler原则将九段沙潮沟进行了分级。然后使用网格法对各个等级的潮沟进行了分维研究,计算了九段沙不同等级的每个潮沟左右两侧的维数值,并结合潮沟的宽度大小,对其维数值进行了比较和分析。研究结果表明,九段沙相同等级潮沟中,潮沟左侧维数的变化范围大于右侧,即潮沟左侧发育的复杂程度大于右侧;不同等级潮沟宽度的最小值变化幅度不大,但潮沟宽度的最大值变化幅度较大;不同等级潮沟宽度的变化和其潮沟左右两侧维数差值变化的相关性较小;不同等级潮沟,无论左侧还是右侧,潮沟维数大小随着潮沟的等级数和潮沟的平均宽度的增大而增大。

Taking tidal channels at the Jiuduan Shaol in Yangtze River Estuary as a research case, information of which was extracted from Landsat-8 remote sensing image of panchromatic band on August 13, 2013, tidal channels were graded by using the principle of Horton- Strahler. Fractal dimensions research was conducted by using the grid method for various grades of tidal channels. Fractal dimension values at both left and right sides were calculated for each grade of Jiuduan Shaol tidal channels. Taking the width of the tidal channels into consideration, fractal dimension values were compared and analyzed. We find that the same grade of Jiuduan Shaol tidal channels, which on the left side of the dimension change range are greater than that on the right, namely that the tidal channels on the left side are more complex than those on the right. The change of minimum width of different grades of tidal channels is little, but that of the maximum is much. There is little correlation between the changes in the width of the different grades of tidal channels and its fractal dimension difference values between left and right sides. In different grades of tidal channels, whether left or right, fractal dimension values increase with the average width and the grade number of tidal channels.