On Fractals and Fractal Dimensions of Local River Systems in Hilly Area of Sichuan Basin

Based on the ArcGIS9.3 software,this paper discusses the application of the fractal and fractal dimension theory of local river systems in hilly areas of Sichuan basin through choosing the Wuyi River system and the Shimen River system as the study samples.The results are as follows.(1) The stream ramification ratio,the length ratio,the area ratio and the gradient ratio of the Wuyi River system are 2.88,1.86,2.29 and 1.72,respectively.The Horton ratios in the Shimen River system are 3.32,1.89,2.15 and 2.48,respectively.Both belong to the primary growth drainage systems,the fractal dimension value being 1.05 for the Wuyi River system and 1.00 for the Shimen River system.(2) The fractal and fractal dimension characteristics of the local river systems in hilly areas of Sichuan basin are not completely the same as those in large scale watersheds.The stream ramification ratio can accurately reflect the level of stream development between adjacent waterways.The Wuyi River system with relatively complex high level of development is more likely to have big difference with the river systems in large scale ones on the fractal value.(3) Research on the fractal and fractal dimensions of local river systems contributes to learning more about the local river systems,to helping the analysis of the water balance in local agricultural catchments,to promoting the reasonable arrangement of the irrigation and drainage engineering and,finally,to achieving the optimal allocation of the water resources in agriculture.