本文从坡面与沟谷侵蚀、河床演变及河型转化方面,讨论了地貌过程从数量的变化达到了某一个最高点(内部界限),引起了地貌系统的分解,发生了质的变化,以及它们又是在怎样的条件下(外部界限)相互转化的.指出识别这类地貌界限,对于防治水土流失及控制冲积性河流都有重要意义. In this paper, we discuss the change of the number of topographic processes from one to the highest point (internal limit) in terms of slope erosion and valley erosion, river bed evolution and river type transformation, which leads to the decomposition of the landscape system and the qualitative changes that have taken place And under what conditions (external boundaries) transform each other, pointing out that identifying such boundary of geomorphology is of great significance to preventing and controlling soil erosion and alluvial rivers.