Abstract: Selecting Manting river reach as the sample,the plain-form,characteristics of the flow and riverbed evolutionary regularity are discussed by generalized fixed-bed and mobile-bed river engineering model.Results show that the surface curve of the bottle-neck reach is polygonal line,and riverbed evolution represents the characteristics of fluctuating backwater area and plain tract such as scouring when water flooding,falling and at upper course ,filling when water rising ,in falling water stage and

Key words: bottle-neck reach, riverbed evolution, Lancanjiang

摘要： 以澜沧江曼厅卡口河段为例,通过概化定床河工模型和动床河工模型试验,探讨了卡口河道的平面形态,水 流特征及河床演变规律.得出以下结论:??卡口河道的水面线是折线型曲线;??河床演变具有洪冲枯淤、涨淤落冲、 上冲下淤等变动回水区河道的特性;??卡口河道涨水变形小、落水时会形成横向切割冲刷水流,导致边滩、河岸倒 塌拓宽,形成多汊道浅滩、散乱浅滩或游荡性浅滩等

关键词: 卡口河道, 河床演变, 澜沧江