水系的分形维数及其含义

THE FRACTAL DIMENSION OF RIVER NETWORKS AND ITS INTERPRETATION

在分述水系分维数的几个计算方法基础上,对两个试区采用地图照相缩小后扫描以及遥感图象处理的方法提取河流信息,以计盒方法计算水系的分维数,并据此提出划分流域地貌侵蚀发育阶段的方法.

This paper describes the fractal characteristics of river network, the computation methods and the interpretation of the fractal dimension of the river networks. Based on the calculation of fractal dimension in fourteen large basins and sixty-seven subbasins in China the following points are pointed out in this paper;(1) The river networks are fractals. Their geometric structrures has some self-simial-rity.(2) The fractal dimension of river networks can be computed by box counting method. Suitable box size should be selected before reliable result can be got.(3) The real river system is too complicated to be described by just one fractal dimen-sion. Multi-fractals is more suitable for depicting large river systems. Because the large river basins have many subbasins. And in every subbasin, the environment is quite differ-ent and there can be calculated a dimension.(4) The fractal dimension of river network reflects the degree of the river evolution. Using the fractal dimension, we can divide the evolution stages of the cycle of erosion through which the river systems are on. The larger the fractal dimension, the later the stage. The threshold for separating the three evolution stages are : D=1. 6 and D=1. 89. These two values remain further improvement.