切沟、切沟侵蚀与预报

切沟以不能横过耕作为其主要特征，主要在成土母质及疏松的基岩中发展，其沟形不能为一般耕犁所消灭．切沟纵剖面与所在坡面基本一致，横剖面一般为U或V字形．地形和人为因素是切沟发生的决定因素，其中又以人为因素为主．切沟侵蚀发展的方式主要有沟头的溯源侵蚀，沟坡的横向侵蚀发展，及垂向的下切侵蚀，在其它条件相同的情况下，下切的强度取决于地形能量．切沟预报模型的发展经历了70年代的随机模型，80年代的过程模型，以及90年代实用化的过程．模型的研究可以增进我们对切沟何时、何地和什么样发展的理解。

Gully, Gully Erosion and Prediction

Gullies have been defined as stream channel whose width and depth do not allow normal tillage. It mainly occurs in smooth soil or soft bedrock. The valley floor of gully often has same gradient with the land slope where it developed. The cross profile of gully usually is U or V shape. Occurrence of gullies depends on the surface morphology and artificial factor. The development of gully is related to headcut, gully side failure and gully floor cut. The rate of cut is decided by the runoff potential energy supplied by different slope. Modelling the development of gully began in earnest in the 1970s with the most models concentrating on the stochastic reproduction of the badlands. The 1980s saw the introduction of models based on process laws in an attempt to understand the theories behind gully initiation. The 1990s have seen the development of more realistic models that combine processes occurring on hillslopes and within channels to reproduce, and to attempt to understand further, gully development. Theroretical medelling may provide the way forward in furthering our understanding of when, where and how gullies develop.