中文摘要：

维持黄河下游主槽断面良好的形态和大小对保障河道的排洪输沙功能至关重要,而平滩流量是一个能够综合反映主槽形态和大小的指示性因子。本文利用实测水文数据,分析了非漫滩情况下流量-流速关系,认为在非漫滩情况下,尽管平滩流量越大,洪水输沙效率越高,但当平滩流量大于5000-5500m^3/s后,其单位水量的输沙能力增加甚微;而且,从与未来洪水相适应角度,下游平滩流量也不宜大于5000m^3/s,否则将降低其输沙效率。文章还分析了不同平滩流量对排泄设防大洪水的影响,认为平滩流量达4000m^3/s以上才可基本满足防御大洪水的要求,应作为平滩流量下限。基于此,文章建议将＂平滩流量4000-5000m^3/s作为黄河下游健康主槽的标准。进一步分析了下游汛期水量与主槽的响应关系,认为小浪底水库拦沙期结束前下游平滩流量恢复目标宜为4000m^3/s左右。

英文摘要：

The main channel of the Lower Yellow River is the main path to deliver floods and sediment to the delta,so it＇s very important to keep a proper size and figure for the main channel.The bank-full discharge is a suitable parameter to reflect its size and figure,but it has become smaller and smaller since 1986.Based on the observed data from 1950 to 2006 in the lower Yellow River,the relationship between discharge and velocity at some typical cross sections for the floods within the main channel was studied and concluded that the bigger bank-full discharge caused more effective to transport sediment.However,when the bank-full discharge is larger than 5000～5500m^3/s,the efficiency increases little.As for the flood control,the bank-full discharge should be larger than 4000m^3/s and（4000）～5000m^3/s is fit to the future flood situation.Then the paper suggested that the 4000～5000m^3/s should be taken as the restoration target of the main channel in the lower Yellow River.