摘要
按基底地形成因,黄土塬可分为原塬、麓塬、继塬和积塬.各类塬的分布、层序均存在差异.在第二外流期,黄河塑造了晋陕峡谷,分割了主谷两侧麓塬,使麓塬区水土流失由匀速侵蚀区经过激增侵蚀而变为现代的衰减侵蚀区.因支谷下切滞后于主谷,衰减区随裂点后退而扩散,吞食侵蚀激增区.根据一级支流裂点后退速度推算,至少在60万a以后黄土高原水土流失才可能完全变为衰减侵蚀状态.
Based on the formational cause of initial landform, the loess yuan is subdevided into: the initial yuan, the piedmont yuan, the succeeded yuan and depositional yuan. Each of them is different from others in the distribution and the sequence. During the second outflow period of the Yellow River, the gorge between Shanxi and Shanxi was formed, the piedmont yuan on each side of the main current was cut apart, and as a result of increased erosion, the region of the piedmont yuan was changed into the declining eroded region from the even eroded region. Because the cutting of the tributaries lags behind the main current, the increasing eroded regions were engulfed by the increase of the declining eroded regions following the drawback of the knick points. According to the drawback speed of the first grade tributaries, it will take at least 6×10~5 years that the erosion in the Loess Pleteau could be changed into declining eroded state.
出处
《北京师范大学学报（自然科学版）》
CAS
CSCD
1990年第1期76-83,共8页
Journal of Beijing Normal University(Natural Science)
基金
"七五"攻关项目
关键词
黄河
演变
水土流失
黄土高原
扩散
the Loess Pleteau, the evolution of Yellow River, regional diffuse modle of erosion.
