黄河下游高含沙洪水河床形态及调控指标

利用水库调控高含沙洪水是维持黄河下游主槽不萎缩的重要途径。基于黄河下游实测高含沙洪水冲淤特性的分析,按流量大小对高含沙洪水进行了分类,提出了黄河下游高含沙洪水的分类调控思路及相应的调控指标。大漫滩高含沙洪水,在满足黄河下游防洪要求的前提下,控制洪峰流量大于1.5倍的平滩流量,来沙系数在0.012~0.04 kg·s/m~6范围内。一般高含沙洪水,控制黄河下游洪水流量接近平滩流量,并尽可能控制来沙系数在临界值附近。高含沙小洪水,控制黄河下游洪水流量在2 500 m~3/s以下,洪水沙量小于2亿t。高含沙洪水经过分类调控后,可较大限度地利用滩地淤沙、主槽输沙能力排沙及花园口以上较大的主槽库容滞沙,维持或提高黄河下游主槽过流能力。

Regulation indices of hyperconcentrated floods in the Lower Yellow River

Regulation of hyperconcentrated floods by reservoir is an important approach to maintain health of main channel in the Lower Yellow River (LYR).Based on analysis of hyperconcentrated floods in the LYR,the floods are classified into 3 types,and classification regulation idea and indices are proposed in this paper.For large overbank floods,peak discharge in the LYR should be controlled as 1.5 times of bankfull discharge,incoming sediment coefficient should be controlled in range of 0.012-0.04.As to ordinary hyperconcentrated floods,the discharge should be kept close to bankfull discharge,and incoming sediment coefficient should be around threshold value for erosion and deposition.For lower hyperconcentrated floods,the discharge should be controlled less than 2500m3/s,and sediment load should be less than 0.2 billion t.After the classified regulation,broad floodplain in the LYR and main channel volume upstream from Huayuankou station can be used well to store sediment.As a result,main channel conveyance capacity will be best to transport incoming sediment,and the flow conveyance capacity of main channel in the LYR will be increased.