黄河下游花园口河段洪水涨落过程中河床横断面形态的调整

利用黄河下游1950-1985年间218场洪水资料,讨论了黄河下游花园口河段洪水起涨和回落过程中河床形态调整的不同过程.在洪水起涨阶段,花园口河段河床宽深比以增大为主,且洪水最大含沙量越大,宽深比增大的幅度越大,洪峰增幅比在3以下时,宽深比随最大含沙量的增大而增大,洪峰增幅比在3以上时,呈随含沙量的增大而减小的趋势.在洪水回落阶段,宽深比的变化方向则相反.在含沙量较小时,河床宽深比的减小主要发生在洪水起涨阶段,在含沙量很大时,河床宽深比的减小主要发生在洪水回落阶段.

Channel deformation at the wandering-braided reaches of the lower Yellow River at rising and falling stages during the period of flood events

Based on the 218 flood events data of the lower Yellow River from 1950 to 1985,different channel transverse adjustment at Huayuankou reaches of the lower Yellow River at rising and falling stages during flood events are distinguished.At the rising stage,the width to depth ratio at Huayuankou reaches exhibits the tendency of generally increasing.The higher the maximum sediment concentration of the flood events,the larger the width to depth ratio.When the flood peak-increasing ratio is lower than 3,the width to depth ratio is in direct rat io to it.When it is higher than 3,the width to depth ratio is in inverse ratio to it.At the falling stage,the situation is just on the contrary When the maximum sediment concentration of the flood events is lower than 15 kg/m³ or higher than 300 kg/m³,the width to depth ratio is in net decrease.When the flood peak-increasing ratio is higher than 3,the width to depth ratio of the most flood events will decrease.The deformation of the channel during flood events is firmly related to sediment concentration.When the sediment concentration of the flood events is low,the decrease of the width to depth rat io is mainly at rising stage.When the sediment concentration of the flood events is high,the decrease of the width to depth ratio is mainly at falling stage.