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黄土丘陵沟壑区地形破碎,各种侵蚀十分活跃。由于坡度和坡面位置的不同,这些侵蚀过程具有明显的垂直分带性(图1)。在顶部坡面(1区和2区),坡度由1区的几度增加到2区的35°,这里多为坡耕地,部分已辟为梯田,主要的侵蚀过程是溅蚀、面蚀和细沟侵蚀。2区下部的坡段存在一明显的转折,坡度往往陡增到40°以上(3区),土地利用方式主要为草坡。3区重力侵蚀和沟道侵蚀活跃,除地表侵蚀之外,洞穴侵蚀较发育,其入口多发育在1区和2区,而出口则往往出现在3区。谷坡的底部坡度平缓(4区),是坡面径流、泥沙流向沟口的通道。
The loess hilly and gully areas are fragmented and all kinds of erosion are very active. Due to the difference of slope and slope position, these erosion processes have obvious vertical zonation (Figure 1). On the top slope (Zone 1 and Zone 2), the slope increased from a few degrees in Zone 1 to 35 ° in Zone 2, mostly sloping arable land and partly terraced fields. The major erosion processes were splashing, surface erosion and Rill erosion. There is a clear turning point in the lower part of Zone 2, and the slope often increases sharply to more than 40 ° (Zone 3). The main land use pattern is grass slope. Gravity erosion and channel erosion in Zone 3 are active. Except for surface erosion, cave erosion is more developed. Its entrances are mostly developed in Zone 1 and Zone 2, while exports are often found in Zone 3. The bottom slope of the valley slope is gentle (Zone 4) and is the channel for runoff and sediment flow to the Mizoguchi.