一、引言黄河包头孟津间流域面积约三十四万平方公里内,除掉河谷平原以外,大都是山岳和丘陵。其中大部为黄土。黄土之下接连以红土或其它冲积土层者,形成土层厚度至二五○公尺以上。基于冲刷的演变,地形上发生极大的变化,更利于 I. INTRODUCTION The Baotou Mengjin drainage area of ​​the Yellow River covers an area of ​​about 340,000 square kilometers. Most of the area except the plains of the valley is mountains and hills. Most of them are loess. Under the loess successively with red soil or other alluvial soil, the formation of soil thickness to more than 250 meters. Based on the evolution of the erosion, great changes have taken place on the terrain, which is more conducive