区域地壳隆升或地槽回返褶皱成山后,斜坡上出现平行状水系.随着河流的溯源侵蚀,分水岭后退,水系适应内外力条件演变成不同型式,并发生河流袭夺.导致河流发生袭夺的决定性原因,一是袭夺河的快速溯源侵蚀,二是位于分水岭反面的高位被袭夺河的河床下与古分水岭下潜蚀作用和块体运动.湔江支流之一海子河在早更新世末依次袭夺了古花园沟河(已消失)和古银厂沟河(原石亭江右支流)等河.

Parallel drainage systems occur on the slopes soon after a mountain has been formed.Along with the retrogressive erosion of rivers,drainage divides are migrating. Drainage systemsadapt to their inner and outer dynamics and develop into various types. Some rivers are capturing each other during the development of the drainage systems. There are two crucialcauses of the river capturing. One is the rapidly retrogressive erosion of the capturing river.The other is the suberosion and mass movement under the river beds of the pirated rivers andthe ancient drainage divides. The ancient higher pirated rivers were located at the oppositeside of the ancient drainage divide. Haizihe, one of the branches of the Jianjiang River,canbe taken as an example of river capturing. It captured ancient Huayuangou River (since disappeared) and Yinchanggou River(former right branch of the Shitingjiang).