渭河陕西段河床沉积物的粒度参数分析

Parameter Analysis on Grain Size Distribution of Streambed Sediment in the Weihe River of Shaanxi Province

在渭河陕西段选取眉县、咸阳、西安、临潼、华县5个研究点,通过对河床沉积物样品的采集与粒度分析,分别采用Folk-Ward图解法公式和McManus矩法公式,对5个研究点沉积物的粒度参数进行计算和比较。结果显示,两种方法计算得出的5个地点沉积物平均粒径和分选系数基本相同,但偏度和峰度计算结果相差较大。图解法计算结果中除西安草滩外,其他4个采样点粒径均符合正态分布;矩法计算出的偏度和峰度的数值超出了所规定的描述范围。从两种分析方法来看,渭河表层沉积物粒度分析更适合用图解法进行计算和描述。

Estimation of grain size distribution is of great importance in determination of streambed hydraulic conductivity. In this paper,streambed sediment samples from five study locations including Meixian, Xianyang, Xi＇an, Lintong, and Huaxian in the Weihe River were collected. The parameter characteristics of grain size distribution for those sediment samples were analyzed and compared using the Graphical Method of Folk-Ward formula and McManus moment method. The results showed that the average particle diameter and separation coefficient of those sediment samples from the five sites have the same variation but high difference of skewness and kurtosis. Except for the Caotan of Xi＇ an station, the grain size distribution of streambed sedi- ments from other four sites is in normal distribution based on the graphical method. However, the skewness and kurtosis values calculated by the moment method exceed the predetermined ranges. Comparatively, the graphical method is more suitable for the grain size analysis of streambed sediments in the Weihe River.