Analysis of Local Water System in Qingjiang River Basin based on Box Dimension Method and Its Fractal Dimension Characteristics

The estimation of river development degree is of vital importance for the water management and hydrology site optimization. The precision of river network development degree analysis is largely dependent on the accuracy of river basin water extraction. Taking Yichang section of the Qingjiang River Basin as the research subject, this paper extracts the river network based on the digital elevation model data. The drainage density and fractal dimension based on box counting method are calculated in each simulative river network under different flow threshold, and the fractal dimension characteristics are discussed as well. Flow threshold and drainage density and fractal dimension are fitted in order to determine the appropriate flow threshold, and its corresponding fractal dimension is taken as the basis to determine the degree of river development. The results show that:(1)The smaller the threshold value is, the more intensive the river networks is, consequently the bigger the fractal dimension and drainage density is. Meanwhile, there are clear logarithm relationships between the threshold and the fractal dimension and drainage density. (2)The value of fractal dimension of the river network is 1.004(less than 1.6), which indicates the network is still in the young stage of erosion and development.