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2006年6月,按照泥沙旋回分层连续取样,分析了黄土高原丘陵沟壑区典型小流域1954年修建的淤地坝泥沙粒径的剖面分布特征.结果表明:该坝地泥沙旋回至少28个,旋回层的厚度范围在2～60cm;沉积剖面土壤粒径以粉砂(0.05～0.002mm)为主,占60%以上,其粒径集中分布于0.01～0.05mm,粗泥沙(粒径>0.05mm)含量约占23.09%;随淤积深度的增加,泥沙各粒径范围的变异程度增加,2m土壤深处可作为研究区淤地坝粒径变异突变点的标识,粒径变异是河道比降和水沙动力条件共同作用的结果;研究区淤地坝泥沙沉积剖面存在72cm厚的累积耕作层,累积耕作层的明确对于淤地坝泥沙侵蚀环境具有指示作用.
In June 2006, according to the stratified continuous sampling of sediment swirling, the profile distribution characteristics of sediment particle size of silt dams constructed in 1954 in a typical small watershed in the hilly area of the Loess Plateau were analyzed. The results show that the sediment swirling of the dam at least 28, and the thickness of the cyclotron ranges from 2 to 60 cm. The sediment profile is dominated by silt (0.05-0.002 mm), accounting for more than 60% of the total sediment. Its particle size is mainly distributed in the range of 0.01-0.05 mm. With the diameter of sediment> 0.05 mm) accounted for about 23.09%. With the increase of deposition depth, the degree of variation in each particle size range of sediment increased, and the depth of 2 m could be used as the marker for the variation of particle size of check dams in the study area. Variations are the result of the combination of channel specific gravity and water-sand dynamic conditions. The 72 cm thick tillage layer exists in the sediment depositional section of the siltation dam in the study area. The clear tillage layer has an indication of the silt erosion environment in the silting dam.