中文摘要：

通过理论分析和实测资料计算，阐释了黄河糙率异常现象并对其偏小的原因背景进行了剖析，认为导致黄河河槽糙率异常的主要原因，首要是套用清水定床条件下的时均流阻力计算公式，其次是计算所用水文实测资料难具代表性；同时指出曼宁公式无法良好适用于动床阻力计算，已有的动床阻力研究成果在理论上进展有限，也难有实用性强或精度高的计算公式；进一步通过阐述水深指数的影响因子及表达形式，提出了解决黄河河槽糙率异常的修正途径，使修正后糙率的点群关系得到改善，物理含义也得到保证。最后，根据本文方法修正后的花园口水文站糙率资料，建立了糙率同流量的经验关系式，进而可连同动床阻力修正公式预测不同来水来沙条件下的平均流速。黄河实测资料的检验结果表明其预测精度较高。

英文摘要：

The abnormal roughness problem of the Yellow River is expounded in this paper and the reasons why the roughness is taken too small has been analyzed through theoretical analysis and measured data. The main reasons for the abnormal channel roughness of the Yellow River are： （1） using a flow resistance formula for the time averaged flow in the fixed bed conditions, （2） using inadequete representive hydrologic data. It is pointed out that the Manning＇s formula is not suitable for movable bed resistance calculation. The existing research results of movable bed resistance are limited in theoretical progress, and it is hard to find a formula with strong practicality or high precision. Further more, a correction solution has been put forward to solve the abnormal channel roughness of the Yellow River by describing the impact factors and their expressions of the depth index, which improved the relation graph of roughness and guaranteed its physical meaning. Finally, according to the adjusted roughness data of the Huayuankou Hydrometric Station, an empirical equation of roughness with flow quantity has been established, by which the average velocity in different incoming water and sediment conditions can be predicted together with the modified resistance formula of movable bed. The test result shows that the prediction accuracy is better in processing the measured data of the Yellow River.