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严格地讲,在一定的相对稳定的地质时期内,水土流失受控于两种外力的作用,即涉及气候、地貌、植被、土壤等自然因素的外营力和人类活动.实际上,人类活动并不像地表径流等外营力那样直接参与侵蚀过程的发生,但人类活动的结果使水土流失过程发生了改变,使自然侵蚀过程大大加速.研究表明,在现代地质和气候未发生显著变化的情况下,人为活动特别是人为作用造成的天然植被的破坏是黄土高原现代水土流失加剧的根本原因;黄土高原土壤侵蚀的速率已由唐代以前7.9%的自然侵蚀速率上升到今天的25%.50年代我国的水土流失面积为153万km~2,1992年公布的遥感技术普查结果是水蚀面积179.4万km~2,40年来已治理53万km~2.也就是说,若不考虑其他原因,40年来以人类活动为主要原因的水蚀面积扩大了79万km~2.因此,人类不合理的社会经济行为是现代加速侵蚀的主导因素.
Strictly speaking, within a certain period of relatively stable geology, soil erosion is controlled by two external forces, namely, external forces and human activities involving natural factors such as climate, landform, vegetation and soil, etc. In fact, human activities Is not as directly involved in the erosion process as surface runoff and other external forces, but the result of human activities has changed the process of soil erosion and greatly accelerated the natural erosion process.Research shows that in the modern geology and climate did not change significantly Under the circumstance, the destruction of natural vegetation caused by man-made activities, especially man-made effects, is the root cause of the intensified soil and water loss in the Loess Plateau. The rate of soil erosion in the Loess Plateau rose from 7.9% of the natural erosion rate before the Tang Dynasty to 25% today. In the 1950s, the area of soil erosion in China was 1.53 million km ~ 2. The results of the remote sensing technology survey released in 1992 showed that the water erosion area was 1,794,000 km ~ 2, and it has been treated 530,000 km ~ 2 in 40 years. That is, if we do not consider other reasons In the past 40 years, human activities as the main reason for water erosion area expanded by 790000 km ~ 2. Therefore, unreasonable social and economic behavior of mankind is the leading factor in accelerating the erosion of modern times.