“分水岭迁移与河流袭夺”客观存在

分水岭迁移的结果必然会引起河流的袭夺，这是水系演变中的客观规律。分水岭之所以会发生迁移，关键在于分水岭两侧分别存在着高位河流与低位河流，这就使得分水岭两侧的侵蚀能量有差异。分水岭的被切穿主要是由于低位河流溯源侵蚀较强，迫使分水岭向高位河流的一例移动，并最终袭夺高位河流。

OBJECTIVE REALITY OF WATERSHED SHIFTING

There are the hish level river and the low level river on the sities of the watershed. Conse-quentiy,the waterslied must be shifted. The high level river ,that is the erosion level and its longprofile, is higher than the low lever river. So lons as the clinlatic conditions(the river discharses)are not a great disparity on both sides of the watershed, the erosion energy differences betweenthe high lcvel river and the low level river wiil arise.The relative altitude of the fow level river is higher than that of the high level river fromshifting ridge to local base level of erosion. More spocifically the waterslied sliifting and rivercapture are directly controlled by the low level riverfsee Fig. 13. That is to say the mass move-ments including slide, slip and flow are active nearby the piracy knick point across the crosssection of the high level river. The watershed is greatiy broken and cut by the low level river.Therefore ,the high level river is captured.The high level riveris meandering can not cut the waterehed ,nor annex it across the drainagearea of the low level river.The flood of a dyke on the plain does not belong to the river capture.