黄河内蒙古段不同粒径泥沙输移能力变化分析

Variation of Sediment Carrying Capacity of Various Particle Sizes in Inner Mongolia Reach of the Yellow River

泥沙输移的效果不仅受水流和边界条件的影响,同时也取决于泥沙自身的特征,包括泥沙数量的多少和泥沙粒径的分布特征.以黄河内蒙古段1958-2013 年实测水文资料为依据,分别将巴彦高勒和头道拐断面作为内蒙古段上下游控制断面,将泥沙分为小于0. 010 mm、0. 010 ～0. 025 mm、0. 025 ～0. 050 mm、0. 050 ～0. 100 mm 及大于0. 100 mm 5 个粒径组,探讨了各粒径级泥沙在不同时期的输移能力.结果表明：①历年洪水过程中分组沙与全沙呈较好的正相关关系,粒径级0. 025 ～0. 050 mm 的泥沙输移对全沙的贡献最大,粗沙次之,贡献最小的为细沙;②水力条件改变时,巴彦高勒断面的河床冲淤调整较下游头道拐断面表现得更为明显,特别是在粒径小于0. 010 mm 的细沙输移能力变化方面,不过随着来水在年际间和年内趋于平均,细沙的输移变化也愈发均匀.

The effect of sediment transport is not only affected by flow and boundary conditions, but also depends on the characteristics of the sediment itself, which includes sediment quantity and distribution characteristics of particle size.Based on the 1958-2013 observed hydrologic data in Inner Mongolia section of the Yellow River, this study respectively discussed the sediment carrying capacity of various particle sizes in different periods on the conditions that the sediment was divided into five grain size fractions ( smaller than 0.010 mm, 0.010-0.025 mm, 0.025-0.050 mm, 0.050-0.100 mm and greater than 0.100 mm).The results show that there is a good positive correlation between every sediment groups and total sediment in the annual flood processes.The sediment transport of the particle size between 0.025 and 0.050 mm makes the greatest percentage and coarse sand takes the second place and the least is the fine sand. Meanwhile, under the change of hydraulic conditions, the adjustment process of river bed scouring and deposition on Bayangaole section is more obviously than that of the Toudaoguai Section, especially in sand transport capacity of particle size less than 0.010 mm.However, as the runoff tends towards mean within a year and annually, the transport capacity of fine sand is also increasingly uniform.