弯曲河流塑造实验与维持条件综述

Review on experiments of meandering river formation and sustaining conditions

弯曲河流横向迁移的渐变过程和裁弯触发的突变过程,使得野外观测其全演变周期具有很大难度,因此开展室内水槽实验塑造和模拟弯曲小河演变具有可操作性和可控制性。通过系统地总结室内水槽塑造弯曲河流实验的实验条件与研究结果,从影响弯曲河流形成与演变的关键因素如水流、泥沙、比降和植物四个方面,对以往水槽实验成果进行对比分析。指出了前人实验研究尚未解决的若干问题,提出从正过程（弯曲至辫状）和逆过程（辫状至弯曲）两个方向去设置水槽实验条件,以期获得弯道演变的维持条件和确定弯曲-辫状相互河型转化的临界水流-泥沙-植被阈值。

Processes of lateral migration and cutoff occurrence in meandering rivers generate very high difficulties on field investigation and observation,so naturally forming and modeling a small meander channel in laboratory experiments performed by researchers are operational and controllable. Experimental conditions and main results of pervious laboratory experiments are summarized systematically and compared,including critical factors（flow,sediment,slope,vegetation） of influencing bend formation and evolution. Some unsolved problems in flume experiments are addressed as well. Furthermore,new experimental conditions shall be designed to uncover the positive processes from meandering to braided channel,and the reverse processes from braided to meandering channel,so as to identify sustaining conditions of meandering channel formation and the flowsediment-vegetation threshold of mutual transition of meandering-braided pattern.