长江中上游地区土壤侵蚀机制及过程试验研究

基于中国大陆水蚀地区土壤侵蚀的主要影响因子-土壤抗侵蚀性指标进行的35个一级控制性测点试验对比研究和野外人工降雨原位试验,重点讨论了长江中上游地区土壤侵蚀形成的机制和过程。结果表明长江中上游地区土壤侵蚀主要表现为在降雨和土壤蓄满壤中流参与下的重力侵蚀过程。在形成上表现为坡地上土壤体表层小范围的滑动和微型阵性泥石流过程,导致沟道河流泥沙输移比小并产生局部严重淤积,土壤侵蚀的危害首先表现为土层进一步变薄、退化和荒芜,其次表现为泥沙游积和洪害。长江中上游地区土壤保持的基本方针应该是“保土减水”,与黄土高原“全部降水就地入渗拦蓄”的方针有所不同。

ON SOIL EROSION MECHANISM AND PROCESS IN MIDDLE AND UPPER REACHES OF CHANG JIANG RIVER

Based on main factors-soil anti-erodibility of the water erosion area in mainland of China,the tests of thirty five first-class controlled spots are comparatively studied. The mechanism and the process of the soil erosion in middle and upper reaches of Changjiang River are discussed emphatically. The results show that the soil erosion in middle and upper reaches of Changjiang River is occurred as the gravity erosion courses when the rain infiltrates as the soil water,and formally as slipping of a small scope of surface soil body of a slope and miniature intermittent debris flows which make silt delivery ratio of the rivers decreased and serious deposit occurred partly. The harm of soil erosion represents that firstly it causes the soil layer thinner, more degenerated and deserted,and secondly the silt deposits and flood occurred. The basic soil conservation principle in middle and upper reaches of Changjiang River should--be"to conserve soil and reduce water",but not"all rain be infiltrated and intercepted into soil"just like in Loess Plateau.