摘要
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。
Varieties of erosion take place frequently in hilly rolling loess region. Erosion process has distinct vertical zonal formation from top to bottom of the slope. Rill erosion is the main type on surface of the slope,which may produce runoff with high sediment concentration,sometimes as high as 600 g/L. Major types of gravity erosion in loess soil are collapse,landslide and slumping,in which collapse and landslide take place frequent-
ly in first order gullies and landslide and slumping in second order gullies. Cavernous erosion often developed due to relatively concentrated seepage flow caused by an abrupt change in hydraulic gradient. It is often located in the edge of gully,the borders of terraced fields and the head of gully. The inlet is often on the top of slope and the outlet usually is located above the local impermeable layer. Nutrition loss in soil is closely related to soil erosion in which 98% of nitrogen loss was caused by soil loss. The overall strategy for soil management on slope farmland is to ameliorate the soil, increase the capability of infiltration and reduce erosion and runoff. At present, the main measure is to break down the crusting surface wholely or partly before rain. The study on transportation mechanism of nutrition and organic matters must be strengthened and attention should be paid to the effect of accelerated erosion by human activities on soil erosion.
出处
《中国水土保持》
北大核心
1991年第11期19-22,共4页
Soil and Water Conservation in China
