长江流域水系分形结构特征及发育阶段划分

Analysis on fractal structural features of Yangtze River water system and development stage division

基于分形理论对长江流域不同地貌类型区分别进行了水系分维数的计算,论证长江流域不同类型地貌区域水系存在显著的分形特征,同时通过水系分维数,定量地判断了长江流域不同地貌单元的地貌发育阶段。研究结果表明:①长江流域水系分维数的变化呈现出自西向东逐渐增大的三阶梯分布趋势。②河网密度作为判别水系疏密程度的指标,在整个研究区与水系分维数之间呈现出一定的正相关关系。③除南阳盆地岗地平原外,长江流域其余地貌区仍然处于地貌侵蚀发育的幼年阶段,但不同地貌区之间的发育程度仍然存在较大差异。④在长江中下游低山丘陵平原区,受城市化进程中人类活动的影响,水系复杂程度及流域侵蚀发育程度皆表现出较大的差异性。

Based on fractal theory, the fractal dimensions of different geomorphological regions in the Yangtze River basin are calculated, and it is found that there are significant fractal characteristics of river systems in different geomorphological regions of the Yangtze River basin. Through water system fractal dimensions, the geomorphological development stages of different geomorphological units are quantitatively determined. The results show that: ①the fractal dimension of river system in the Yangtze River basin shows an increasing trend from west to east with three-step distribution. ②the density of river network, an index to judge the degree of drainage system density, is positively correlated with the fractal dimension of river network. ③the development stages of different geomorphological regions in all of the Yangtze River basin are at the age of infancy, except the Nanyang basin, but there are still significant differences in development degree among different geomorphological regions. ④ the river system complexity and the degree of erosion development are significantly diversified in the low-middle mountains and plains of the middle and lower Yangtze River because of urbanization and human activities.