关键词: 沙丘分布, 风沙流结构, 沙漠化, 分形

Abstract: Applying fractal theories to studies of the distributions of sand diameter and dune, the structures of wind-sand flow and the landscape made from dune, oasis, settlement and so on and to the process of desertification, we get the following findings: (1) There are self-similar characters between the distributions of sand's diameter whose difference in fractal dimension shows the regional difference in the distributions of sands. (2) Dune is a typical kind of fractal geometrical entity and there are self-similar characters between the distributions of dune whose fractal dimension is about 1/2 as much as that of the distributions of sand diameter. (3) The fractal dimension of dune's structure has a better relation with velocity of the wind. As an example of Yanjin region of North Henan province, the fractal dimensions of are 1.9951, 1.8426, 1.6958, 1.7711 and 1.2428 respectively when the velocities of the wind are 6.14 m·s^-1, 7.10 m·s^-1, 8.70 m·s^-1, 9.50 m·s^-1 and 10.76 m·s^-1 respectively. The structure of dune is both fractal and multi-fractal. (4) The landscape made from desert, oasis, settlement, and so on has the characteristic of fractal. The fractal dimension of each landscape factor shows its complexity and stability. In the Heihe River drainage area in China, the fractal dimension (D) of each landscape factor and the index of stability (SK) are listed in the paper. From the data we know that the complexity and the level of stability of the natural oasis are the highest in all the landscape factors referred in the study. (5) The process of desertification is characterized with multi-fractal feature. And if the level of desertification is measured with precipitation and velocity of the wind, it will bear certain irregularity.

Key words: distribution of dunes, structure of wind-sand flow, desertification, fractal