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黄土高原地区是黄河泥沙的主要来源区,黄土的特性也直接影响黄河泥沙的特性。2005年至2012年,共采集表底层黄土样本18个和河道泥沙样本28个,采样区域涵盖了黄土高原北部、中部和南部地区以及黄河中下游干支流河道。样本分析表明,底层黄土自北向南中值粒径逐渐变小、黏土含量逐渐增加,反映了黄土的原始沉积特征。表层黄土反映了风化和侵蚀的综合作用,其黏性矿物含量普遍高于底层原状黄土。在受侵蚀作用较大的地区,由于表层细颗粒的流失,导致中值粒径略大于底层黄土。受黄土分布特性的影响,黄河中游支流自北向南挟带泥沙的中值粒径也呈减小趋势。距离河口越远,黄河干流泥沙的中值粒径越大,反映了泥沙的沿程分选沉积特性。河道泥沙中值粒径和黏性矿物含量之间存在良好的对数关系,可以通过此关系式在测得中值粒径的情况下估算其黏性和非黏性矿物含量。
The Loess Plateau is the main source of Yellow River sediment. The characteristics of loess also directly affect the sediment characteristics of the Yellow River. From 2005 to 2012, a total of 18 loess samples and 28 river sediment samples were collected. The sampling areas covered the northern, central and southern parts of the Loess Plateau as well as the dry and tributary rivers in the middle and lower reaches of the Yellow River. The sample analysis shows that the median diameter of the loess from the north to the south gradually decreases, and the clay content gradually increases, reflecting the original sedimentary characteristics of the loess. Surface loess reflects the combined effect of weathering and erosion, and its viscous mineral content is generally higher than the underlying undisturbed loess. In the area where erosion is more serious, the median grain size is slightly larger than that of the loess due to the loss of surface fine particles. Affected by the distribution of loess, the median grain size of sediments carried by the tributaries of the middle reaches of the Yellow River from north to south also showed a decreasing trend. The farther away from estuary, the larger the median diameter of sediment in the mainstream of the Yellow River reflects the sedimentary characteristics of sediment along the process of sorting. There is a good logarithmic relationship between median particle size and viscous mineral content of sediment in the river, and its viscous and non-viscous mineral content can be estimated from the measured median particle size.