Characteristic And Analysis Of Sruface Roughness

Surface roughness often causes accidents of the ground and surface irregularity, obviously affecting surface runoff and erosion. However, variation of surface roughness in the erosion process is difficult to determine, which affects people's awareness of its role on the process of soil erosion. Therefore, it is necessary to monitor variation of surface roughness microcosmically in the rainfall process. Based on this, this paper had a research on artificial hoe widely adopted on the slope farmland of Loess Plateau, artificial digging, contour tillage, straight line slope and so on. Surface soil of arable land in Yangling was used in this study, and a geographical information system (GIS) was used as a platform to establish the micro-surface DEM. Through indoor simulated rainfall experiments, combined with variation characteristics of micro-DEM, variation of surface roughness in the rainfall process was analyzed quantitatively, and the coupling relationship between micro-topography and surface roughness was explored. The main conclusions were as follows:1 Coefficients of variation ( ) for slope elevation under different tillage were less than 0.1, and spatial variation of morphological distribution was weak. Effect of artificial tillage on the overall distribution of slope and the spatial distribution of surface elevation was the most significant, also effect in the different stages of erosion on spatial and temporal variability of slope was different, which spatial and temporal changes of surface slope was largest before and after runoff, and spatial variation of surface slope tended relatively stable after runoff.2 Tillage had some effect on the micro-slope distribution. Compared with straight line slope, variation of micro-slope was in the order contour tillage > artificial digging > artificial hoe, at the same time, effect of rainfall on the micro-slope was relatively obvious. Under sub-rainfall condition, effect of rainfall on micro-slope in the different stages of erosion was: SpE> CE> SuE, and with the slope and rainfall intensity increasing, effect on the micro-slope in the straight line stage increased; Under continuous rainfall condition, with regard to the same rainfall intensity and the same slope, variation of micro-slope was in the order contour tillage > artificial hoe > artificial digging > straight line, and variation of micro-aspect increased with rainfall intensity increasing.3 Micro aspect of different tillage measures always mainly showed southern slope and northern slope, and under sub-rainfall condition, effect of rainfall in the SpE stage on the ?slope micro-aspect was smallest; Under continuous rainfall condition, there was a'W'trend in variation of grid number of different micro-aspect; Under the same slope condition, effect of rainfall on micro-aspect under different tillage was in the order straight line > contour tillage > artificial digging > artificial hoe, and variation of micro-aspect increased with rainfall intensity increasing.4 Compared with straight line slope, surface volume and surface area of artificial digging, artificial hoe, and contour tillage slope varied more obvious. Under sub-rainfall condition, topographic relief of artificial digging and contour tillage slope was more larger than artificial hoe and straight line slope, so changes of surface volume and areas in the SpE stage were large, and afterwards the effect of rainfall on surface volume and surface area was gradually weakened; Under continuous rainfall condition, there was some fluctuation of surface volume and surface area changes with the slope changing; Under the small slope condition, variation was relatively small, and with the slope increasing, variation increases and then later decrease.5 Despite that correlation between micro-aspect of different directions and surface roughness was significant, but variation of micro -aspect had little effect on the surface roughness; But micro-slope and variation of surface roughness were very closely related, and effect of micro-slope on roughness was in the order 0-5°> 20-25°> 10-15°> 25-30°> 10-15°> 30-35°> 35-40°> 40-90°.6 There was a significant linear relationship between surface roughness of artificial hoe, artificial digging and contour tillage slope and surface area of terrain. The surface roughness increased with the surface area of terrain increasing. Compared with artificial hoe, artificial digging and contour tillage slope, the relationship between surface roughness under the straight line measures and surface area of terrain was not well linear. The same tend is between Topographic index(SAI) and surface roughness(R), and their linear relationship is : SAI=0.3968R+0.5541.