黄河内蒙段河道冲淤量与水沙输移过程的关系分析

Relationship between Channel Scouring/silting Amount and Water-sediment Transport Process in Inner Mongolia Reach of Yellow River

根据1952～2003年黄河内蒙古河段实测断面资料分析,天然状态下该河段均处在淤积状态,青铜峡、三盛公水库建成运行初期水库蓄混排清,不同的水沙组合使河道有冲有淤,青铜峡水库蓄满失去蓄混排清功能后,河道又长期处在淤积状态。河道冲淤量与来水量、来沙量的线性组合高度相关,表明该河段冲淤量与河道的水沙组合有直接的因果关系,由此建立了计算河道冲淤量的数学模型。来沙系数是判断河道冲淤变化的关键指标,实测资料分析表明:来沙系数小于或等于0.005时河道发生冲刷,来沙系数在0.005～0.009之间时河道有冲有淤,来沙系数大于0.009时河道发生淤积,来沙系数大于0.015时淤积量趋于稳定,且以1.0为渐近线。

According to the analysis of the observed data from 1952 to 2003, the Inner Mongolia Reach of the Yellow River has sedimentation in natural state. After building and operation of the Qingtongxia and Sanshenggong reservoirs, the muddy water was stored and clear water was discharged, and the different combinations of water and sediment made the channel have scour and sedimentation. When the Qingtongxia Reservoir lost its function of storing muddy water and discharging clear water, however, is the river returned to the sedimentation state. The channel scour, inflow and incoming sediment have a close linear combination correlated, which indicate that there is a direct causal relationship between the channel scour and the combination of flow and sed- iment, so that a mathematical model was set up for calculating the channel scour. The incoming sediment coefficient is key indica- tor of determining channel scour changes. The observed data analysis show that the scour occur in the channel when incoming sediment coefficient is less than or equal to 0.005, the scour and sedimentation occur in the channel when the incoming sediment coefficient is between 0.005 and 0.009, the sedimentation occur when the incoming sediment coefficient is greater than 0.009, and the sedimentation is stable when incoming sediment coefficient is greater than 0.015 with, 1.0 as asymptote.