SCALE RESPONSES OF MICRO-TOPOGRAPHIC FACTORS ON DIFFERENT SLOPE GRADIENTS.

The geomorphological characteristics is the most directive reflection of soil erosion results. The mechanism of erosion processes and the influence of the micro-topographic characteristic value of erosion can be revealed by analyzing the fluctuation characteristics of micro-topography on slope. In this paper, the typical karst area of Huaying City is taken as the research area. The three slope gradients of <25°, 25-30° and >30°, five terrain factor eigenvalues, including average slope, slope variability, surface roughness, terrain relief and variation coefficient of elevation, are selected to compare the statistical distribution, entropy weight index and terrain interpretation rate, and to analyze the differences in the description of micro-topographic characteristics of soil erosion with different gradients and scales. The results show that (1) the difference of micro-topography feature values of steep slope (>30°) is significantly greater than that of gentle slope (<25°), and the steeper the slope is, the greater the coefficient values of terrain variation is, so the characteristic values of terrain factors with strong variability should be used to describe, such as the variation coefficient of elevation, terrain relief and surface roughness. (2) With the increase of micro-topographic scale, terrain relief and variation coefficient of elevation are positively correlated with scale change, while average slope, slope variation rate and surface roughness are negatively correlated with scale change. The characteristics of terrain relief and variation coefficient of elevation coefficient are relatively sensitive to scales factors, which recommended in the study of erosion mechanism at the microscale. (3) The four factors of surface roughness, variation coefficient of elevation, terrain relief and average slope are better used to present the slope micro-topographic characteristics comprehensively. The comprehensive terrain interpretation rate is the highest (more than 90%) at the scale of 0.5-1 m, which can well reflect the characteristics information of the micro-topography feature. [ABSTRACT FROM AUTHOR]