Roughness coefficient and its uncertainty in gravel-bed river
Roughness coefficient and its uncertainty in gravel-bed river
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DOI：
10.3882/j.issn.1674-2370.2010.02.010
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发表时间：
2010-06
影响因子：
4
通讯作者：
Ji-Sung Kim;Chan Joo Lee;W. Kim;Yong-Jeon Kim
中科院分区：
文献类型：
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作者：
Ji-Sung Kim;Chan Joo Lee;W. Kim;Yong-Jeon Kim
摘要利用实测水位和流量资料，估算了卵石河床段的曼宁糙率系数，并对各种糙率系数估算方法的适用性进行了评价。结果表明，糙率系数随流量和水深的增加而减小，在一定范围内基本保持不变。将实测资料计算的糙率系数与其它方法估算的糙率系数进行比较，结果表明，虽然实测值提供了较大流量下的近似糙率系数，但由于实测值的差异，存在较大的不确定性。因此，根据计算变量的变化分析了与粗糙度系数相关的不确定性。平均而言，粗糙度系数增加20%会导致水深增加7%，流速降低8%，但对于某些横截面，水深可能会增加约15%，流速也会相应降低。研究河段。最后，对基于实测数据的粗糙度系数估算方法的有效性进行了检验。流量测量中10%的误差可能导致糙率系数估计的不确定性超过10%，但相应的计算水深和流速的不确定性降低到约5%。反之，也证实了通过现场实测估算糙率系数的必要性。
Abstract Manning's roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.