Research On Fractal Characters Of Geomorphology And Space-Scale Conversion In Typical Watershed On The Loess Plateau

With the watersheds in different geo-morphological types of regions on the Loess Plateau as the research objective, research on fractal characters of geomorphology and space-scale conversion in the watersheds is carried out by the comprehensive application of fractal theory, geomorphology, soil erosion science and GIS technology in this thesis, with the main conclusions obtained in the following:(1) The Three-Dimensional Fractal Information Dimension(FID) GIS model for geomorphology of watersheds is established, and the estimation software system is developed. The Three-Dimensinal FID can effectively overcome the defects of geo-morphological elevation information that can not be directly expressed by Two-Dimensional FID as well as of mono-morphological characters that can only be expressed by slope degree, height difference, and gully density, etc. and also express the factor parameters of the traditional geomorphology and their relationships comprehensively.(2) The relationships between the image element scale and Three-Dimensinal FID as well as between the counter distance and The Three-Dimensinal FID are determined; and the inter-conversion of The Three-Dimensinal FID under the different counter intervals can be realized. The research indicates: it is suitable that the setting of image element scale should be equal to one piece of counter distance value; and the contrast analysis of The Three-Dimensinal FID in the case of different regional geomorphology should be based on the unified image element scale as the prerequisite. There appears to have a better quadratic polynomial function between The Three-Dimensinal FID and the topographical map counter intervals. Accordingly, this relationship can be used to carry out the inter-conversion of The Three-Dimensinal FID under the different counter intervals.(3) The conversion method for the fractal characters of geomorphology under the different space scales is suggested. The inter-relationship between the The Three-Dimensinal FID of geomorphology and the watershed areas under the different space scales on the loess plateau is established. This relationship can be used to carry out the prediction of the The Three-Dimensinal FID of geomorphology from the small scales to the big scales (positive operation) and from the big scales to the small scales (inverse operation), whereby the conversion of the fractal characters of geomorphology under different space scales can be realized.(4) This thesis deals with the fractal changing characters of geomorphology in different types of geo-morphological regions on the loess plateau. The results calculated from the The Three-Dimensinal FID values of typical watersheds indicate that the more complicated the geomorphology is, the greater the The Three-Dimensinal FID values will be, and vice versa. The concrete situations are: the landform or relief complexity at the gully part located in the Nanxiao River watershed in the plateau hilly and gully regions is high, whose value is 2.9402; the Xinzi River watershed located in the Liang (elongated loess mound) and Mao (convex slope)-shaped hilly and gully regions appears to have the tendency of diminishing fluctuation from the upstream to the downstream, whose value is 2.7240-2.9276; the Dali River Watershed located in the Mao shaped hilly and gully regions appears to have linear increase first and then to have the fluctuating changes from the upper to the lower, whose value is 2.1190-2.7141; the Anjia gully watershed located in the long Liang hilly and gully region appears to have the less complicity in total, whose value is 1.7792.