水沙因子对小浪底水库异重流排沙影响分析

Influence of Water Sediment Factors on Sediment Ejection of Density Flow in Xiaolangdi Reservoir

2004-2010年黄河干流汛前水库群联合调度、人工异重流塑造进行了7次,小浪底水库各年份异重流排沙比相差很大,排沙效果并不理想。通过深入分析,得出小浪底水库入库水沙、悬沙细颗粒含量、河堤站水沙变化以及三门峡水库调度与潼关来水组成等因素对水库异重流排沙的影响。结果表明:①入库水沙对小浪底水库异重流塑造起着关键作用;②在异重流塑造期间,入库沙量中细颗粒泥沙含量越高,异重流排沙比就会越大。随着异重流排沙比的增加,分组沙的排沙比也在增大,细颗粒泥沙增加幅度最大;③三门峡水库在下泄大流量清水的过程中,河堤以上河段是冲刷的;在敞泄排沙的过程中,河堤以上河段有冲有淤,在实际操作时可适当控制三门峡出库高含沙水流,来减少河堤以上河段的淤积,提高小浪底水库异重流排沙效果。

From 2004 to 2010, by united operation of reservoir groups before flood seasons, 7 times of man-made density currents were shaped in Yellow River, the sediment delivery rate of Xiaolangdi Reservoir varied considerably, and the effect of sediment ejection is not ideal. This paper analyzes the influence of different factors on current sediment ejection, such as incoming water and sediments, suspended sediment contents, variation of water and sand in Hedi Station, the operation of Sanmenxia Reservoir, and incoming water composition of Tongguan and so on. The results show that： （1）Incoming water and sediment play a crucial role in shaping density current. （2） During the period of density current, if the content of fine sediment is much higher, the sediment delivery ratio will become much bigger. With the increase in sediment delivery ratio of total sand, the sediment delivery ratio of group sediment also increases, and the increase in fine sediment is the most. （3） During the period of large discharge release of clear water from Sanmenxia Reservoir, scouring happens in the upstream of the river＇s Hedi Station. During the period of free sediment release, deposition and scour can perhaps happen in the upstream of the rivers Hedi Station. In actual operation, the hyper-coneentrated flow discharged from Sanmenxia Reservoir can be properly controlled to reduce deposition of rivers upstream Hedi and improve the effect of density current.