| 摘要: |
| 自1999年小浪底水库运用以来黄河下游过渡型河段的平滩流量小于其上下游河段，这种“瓶颈”现象严重制约了小浪底水库排放的洪水量级，研究其床面形态特征及动床阻力的变化对黄河下游河道排洪输沙具有重要意义。本研究采用多波束测深系统对黄河下游过渡型河段床面形态进行了观测，并结合近年来过渡型河段典型水文站的实测流量过程分析了床面形态变化对动床阻力的影响。研究表明:（1）黄河下游过渡型河段在流量低于1500~2000m3/s时床面形态表现为沙垄，且背水面倾角较小，约为6.57°；流量大于1500~2000m3/s时沙垄蚀退，床面形态趋于动平整。（2）过渡型河段在流量低于1500~2000m3/s时动床阻力与综合阻力变化趋势类似；流量大于1500~2000m3/s时，河相系数减小，河道主槽趋向窄深，动床阻力小于综合阻力，岸壁阻力的影响不可忽略。（3）床沙粗化是黄河下游床面形态变化的重要影响因素，当床沙中值粒径超过0.12mm左右时，床面形态变化显著。本研究明晰了黄河下游过渡型河段床面形态转换的流量阈值，揭示了床面形态变化下黄河下游过渡型河段动床阻力的变化规律，研究对小浪底水库调度和黄河下游河道治理具有一定的指导意义。 |
| 关键词: 床面形态 黄河下游:过渡河段 动床阻力 多波束测深系统 |
| DOI： |
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| 基金项目:国家自然科学基金项目黄河水科学研究联合基金（U2243218）；黄河水利科学研究院科技发展基金(HKF202307) |
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| Bed form morphology in transitional reaches of the lower Yellow River and its influence on movable bed resistance |
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zhang guangming, wang ping, geng xu, shen guanqing, zhang yuanfeng
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Yellow River Institute of Hydraulic Research
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| Abstract: |
| Since the operation of Xiaolangdi Reservoir in 1999, the bankfull discharge of the transitional reaches of the lower reaches of the Yellow River is smaller than that of the upper and lower reaches. This "bottleneck" phenomenon seriously restricts the flood magnitude of Xiaolangdi Reservoir. It is of great significance to study the characteristics of its bed morphology and the change of movable bed resistance for flood discharge and sediment transport in the lower reaches of the Yellow River. In this study, a multi-beam sounding system was used to observe the bed morphology of the transitional reach of the lower Yellow River, and the influence of the bed morphology on the movable bed resistance was analyzed based on the measured flow process of typical hydrological stations in the transitional reach in recent years. The results show that: (1) the bed form of the transitional reach of the lower Yellow River are dunes when the discharge is lower than 1500~2000m3/s with small lee slope angles about 6.57°. When the flow discharge is greater than 1500~2000m3/s, the dunes are eroded and the bed form tends to be flat. (2) The change trend of movable bed resistance and Manning resistance is similar when the flow discharge of transitional river reach is lower than 1500~2000m3/s. When the flow discharge is greater than 1500~2000m3/s, the river regime coefficient decreases, the main channel tends to be narrow and deep, the movable bed resistance is less than the Manning resistance, and the influence of bank wall resistance can no longer be ignored. (3) Bed sand coarsing is an essential factor affecting the change of bed morphology in the lower Yellow River. When the median particle size of bed sand exceeds 0.12mm, the bed morphology changes significantly. This study clarified the flow threshold of bed form transformation in transitional reach of the lower Yellow River and revealed the variation of movable-bed resistance in transitional reach of the lower Yellow River under the change of bed shape. This research has certain guiding significance for Xiaolangdi Reservoir operation and river management in the lower Yellow River. |
| Key words: Bed form Lower Yellow River: Transitional reach movable bed resistance Multi-Beam Echo Sounding System |
