Study of Quantization of Topographic Fractal Feature of Small Watershed Model Based on Projective Covering Method

In view of the obvious anisotropy and three-dimensional characteristics of watershed topographic possess,the projective covering method is introduced to quantize fractal feature of three-dimensional surface.Combining the basic theory of fractal dimension of three-dimensional surface calculated by projective covering method and GIS technology,this paper presents the actualization process of GIS on the basis of fractal dimension calculation of three-dimensional surface of watershed geomorphy.And it calculates the fractal dimension of three-dimensional surface of small watershed geomorphy with nine times photogrammetry.The result shows that the projective covering method can realize the quantization of fractal feature of three-dimensional surface of small watershed geomorphy;the calculated fractal dimension can exactly reflect the dynamical characteristics of small watershed geomorphy drived by simulated rainfall;comparing with box-dimension method,the projective covering method can be more favorable in finding out the difference of topographic characteristics under different phases of small watershed.Therefore,it has important meaning in choosing quantization parameters of topographic factors in forecasting model of soil and water conservation.