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在密西西比州古德文河 ( Goodwin Creek)上两个测站点对沙、砾输移作了采样 ,采样流量从刚大于至数倍于床沙的临界剪切应力。从这些样本中计算了河道横断面的典型输移率。输移率的标准偏差近似等于由河床剪切应力引起的群沙平均输移率。所定义的输移率标准化概率密度函数极接近于 γ分布的概率函数。依据这些资料 ,对于一些给定数目的输移率测量值 ,可计算时均输移率预测值的概率精度。
Sampling of sand and gravel transport was carried out at two stations on Goodwin Creek in Mississippi with sampling flow rates ranging from just above to a few times the critical shear stress of bedrock. From these samples, the typical rate of cross-section transport was calculated. The standard deviation of the transport rate is approximately equal to the average transport rate of sand mass caused by shear stress in the riverbed. The defined normalized probability density function of transfer rate is very close to the probability function of γ distribution. Based on these data, for some given number of rate measurements, the probability accuracy of the predicted rate-of-transport can be calculated.