黄河下游高效输沙洪水研究

在进行以输沙入海为目的黄河小浪底水库调水调沙方案的制定时,必须同时考虑两个目标,即(1)提高洪水输沙效率,减少河道淤积;(2)节省输沙用水,降低水资源消耗.同时满足输沙效率较高和输沙用水较省这两项要求的洪水可称为高效输沙洪水.以黄河下游1950-1985年间历次洪水的实测资料为基础,运用统计方法,研究了黄河下游的高效输沙洪水.研究表明,输沙效率随输沙用水的增大而增大,只有某种中等的输沙用水量与中等的输沙效率的组合,才可能是较优或最优的.高效输沙的排沙比可以取为0.85～1.00之间.基于1950-1985年资料进行了研究,结果表明,黄河下游流量在2 600～4 800m~3/s之间,含沙量在30～50kg/m~3之间,排沙比在0.85～1.00之间的洪水,可以作为高效输沙洪水.若考虑排沙比＞0.85,这样的洪水在1950-1985年间的274次洪水中出现过27次.

Study on high-efficient sediment-transporting floods in the Lower Yellow River

One of the objectives of the Xiaolangdi Reservoir on the Yellow River is to regulate flow and sediment processes so that the sediment transport efficiency of the lower Yellow River can be enhanced.For this purpose,two goals should be considered:(1) promoting the sediment transport efficiency to reduce channel sedimentation,and (2) saving the water amount used for transporting sediment to reduce the consumption of water resources.When the floods meet both the above two demands,they can be called high-efficient sediment-transporting floods (HESTFs).Based on the data from the 274 flood events during the period 1950-1985,the HESTFs have been studied by using statistical method.The results show that the sediment transport efficiency of flood events increased with the increase in unit water consumption for sediment transport.However,only the floods events with the combination of medium sediment-transport efficiency and medium unit water consumption for sediment transport could be the optimal.It is suggested that the channel sediment delivery ratio of HESTFs may be adopted as 0.85～1.00.The floods with average discharges of 2600～4200m~3/s,sediment concentration of 30-50kg/m~3,and channel sediment delivery ratio of 0.85～1.00 are the HESTFs.The floods with SDR＞0.85 occurred about 27 times in the 274 floods during the period 1950-1985,which can be used as a reference of optimal combination of flow and sediment load.Based on this rule,the high-efficient sediment-transporting floods in the lower Yellow River can be regulated by Xiaolangdi Reservoir.