在研究分析水库下游河道冲刷侵蚀特点的基础上，分强约束型和弱约束型分汊河道，分别研究其冲刷调整的规律。研究表明：①水库下游河道冲刷侵蚀过程往往存在先刷深、后展宽的冲刷侵蚀特点,河岸河床组成对纵横向侵蚀幅度的影响非常显著。②强约束型分汊河道冲刷调整规律为洲滩形态的调整，沙泓、石泓的下切以及分流比的变化。③弱约束型分汊河道的冲刷调整规律为岸线的崩退，心滩、边滩的切割侵蚀，新的洲滩形成，以及主支汊交替频繁，主泓摆动剧烈，汊道横向摆动大。在此基础上，总结分析了在冲刷调整过程中影响分汊河道演变的关键因素。

On the basis of the erosion characteristic, the erosion adjustment law of braided reach in the downstream reservoir under strong and week constraint conditions is analyzed. The study results indicate as follows: ①The feature of channel scouring course is to degrade first and then widen, the influence of river-bed composition on the magnitude of erosion in longitudinal and transverse directions is very distinct. ②The erosion adjustment process of the strong constraint braided channel shows the river-bed morphology variation, the cut-down of sand channel and gravel channel and change of division ratio. ③The erosion adjustment process of weak constraint braided channel presents as the collapse of shoreline, erosion and cutting of beach, alternating of the main and secondary branches and largely horizontal oscillation of the main channel. And the key factors ?which influence the erosion adjustment of braided reach are also concluded.