Relationship Between Soil Surface Roughness And Rill Erosion In The Process Of Rainfall

Surface roughness is that the results of the land management and soil erosion, it often causes the rugged and uneven surface, serious impact on surface runoff and erosion processes,serious impact on surface runoff and erosion processes. Rill erosion is one of the main ways of soil erosion. Rill erosion refers to the phenomenon of erosion on the surface under the action of the formation of small gully in the slope of the integrated stream after overland flow,including flow on soil separation, erosion and transportation. Surface roughness can be formed directly or indirectly Rill formation, development as well as the size of the rill erosion amount. The formation, development of rill erosion as well as the rill erosion amount can be influenced by surface roughness directly or indirectly. This paper, taking widely used management measures in the Loess Plateau, such as contour drilling, contour dibbling,manual hoeing, contour plowing as the research object, the flat slope as control grope. Use of Lou soil in Yangling area, select different slopes(3°、5°、10°、15°and 20°), different rainfall intensities(60mm/h、90 mm / h and 120 mm / h) and four different tillage measures(contour drilling, contour dibbling, manual hoeing, contour plowing). Through artificial rainfall experiment indoor and outdoor, analysis of different surface roughness on the characteristics of soil erosion and sediment yield。Different surface roughness influenced on rill formation,developmental processes, and the rill erosion amount of research on the relationship between them. Main research results included:(1) Four different tillage measures produces different surface roughness, the size of surface roughness of the four different tillage measures was in order of contour drilling>contour dibbling>manual hoeing>contour plowing>CK.Under the same tillage measures and the same rainfall intensity, the sediment yield increased with the increase of the slope gradient. Under the same slope and rainfall intensity, the sediment yield increased with the increase of the surface roughness except contour dibbling. But there is a critical slope during rainfall, the effect of surface roughness are from increasing erosion to reducing erosion,the critical slope decreases with increasing surface roughness. Through the single factor variance analysis that effect of slope(S),rainfall intensity(P) and surface roughness(RR) to sediment yield(Es) were significant,The relationship between the four type is Es=0.2654P+0.3941S-0.3822RR-0.0528(R2=0.7189).(2) With the increase of surface roughness, rill produced by the late time. In the process of rainfall, the location of each falling-sill bottom is distributed in the middle and lower part of the slope, and the specific location is random, which has nothing to do with the surface roughness.The rill process showed falling-sill bottom—lower cutting groove head—intermittent rill—continuous rill. The rill length sizes under different tillage measures are in order of contour plowing > manual hoeing > contour drilling>contour dibbling. Rill depth and rill horizontal density have the same trend. The rill erosion amount and the slope was significantly correlated. In the same rainfall intensity and slope, rill erosion amount increased with the decrease of surface roughness except contour dibbling. The two have a significant two polynomial relationship. Through the single factor variance analysis that effect of slope(S), rainfall intensity(P) and surface roughness(RR) to rill erosion(Er) were significant,The relationship between the four type is Er=0.2338P+0.4320S-0.1108RR-0.0789(R2=0.6573)...