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以美国《确定洪水频率指南》方法,对中国西部金沙江、雅砻江、大渡河、青衣江和岷江的94个水文站的年最大洪峰系列作特异值检验和偏态系数计算:并对大渡河铜街子站、雅砻江小得石站和岷江紫坪铺站计算了频率洪水。一些站的特异值检测计算表明,特大值的门槛值太高,著名的特大洪水不能被检测判定为特大值,说明用指《指南》方法检测特大值的效果较差。而应用于检测持小值,效果要好一些。根据一个检验标准,剔除经检测判定的特小值后,无疑可以使频率曲线与点据配合较好,舍弃特小值后对计算的稀遇频率洪水值无大影响,可以认为检测特小值的方法,有实用意义。以多站均值方法概化偏态系数获得地区信息,忽视历史信息,使计算频率洪水不准确;应既要地区信息也需注意历史信息,以改进洪水频率的估算。
Based on the “Guideline for Determining the Frequency of Floods” in the United States, the annual maximum flood series of 94 hydrological stations in Jinsha River, Yalong River, Dadu River, Qingyi River and Minjiang River in western China were tested for specific value and skewness coefficient. Tongduzi crossing the river, Yalong River small station and Zijia Pu Min Station Station calculated the frequency of floods. The calculation of the specific value of some stations shows that the threshold value of the super-large value is too high, and the famous super-large flood can not be detected as the super-large value, indicating that the effect of using the “guide” method to detect the super-large value is poor. The small value of the detection used, the effect is better. According to a test standard, excluding the small value of the detection and determination, it is undoubtedly possible to make the frequency curve fit well with the point data. After the special small value is discarded, it has no significant effect on the calculated rare frequency flood value. The method has practical significance. Multi-station means to generalize the skew coefficient to obtain regional information, ignoring the historical information, so that the calculation of the frequency of flood is not accurate; regional information should also take into account the historical information to improve the estimation of the flood frequency.