摘要
通过对淤地坝沟道350个样品粒度特征分析可知：黄土洼沟道沉积物粒度在0.1~250μm之间,以粗粉砂含量最多,占55.50%,其次是极细砂,占21.53%,而细砂和中粗砂含量极少,颗粒整体较细;胶粒、粘粒、细粉砂在垂直深度上分布趋势基本相似,与极细砂和细砂变化趋势相反;根据胶粒、粘粒、细粉砂含量变化,可将沟道发展历史分为三个阶段;剖面在36、58、86、182、292 cm处对应着侵蚀力强的降雨,86 cm对应着历史最强降雨;整个地区平均粒径变化呈现出＂细-粗-细＂的沉积旋回变化规律,408 cm以上沉积层理变化显著,动力环境复杂;以单峰为主,沉积物分选性较差,频率曲线呈正偏和极正偏,峰态有中等和很窄两类;黄土洼地区1963~1986年之间沉积速率较大,1986~1994年沉积速率变慢,1994年之后沉积速率加快。
Based on the analysis of grain size characteristics of 350 samples in check dam of Huangtuwa,the grain size of channel sediments was between 0. 1 μm and 250 μm,which was mainly made up of coarse silt,accounting for 55. 50%,followed by very fine sand,accounting for 21. 53%. The contents of fine sand and medium- coarse sand were extremely low,so the grains were fine on the whole. The distributions of colloid,clay and fine silt in the vertical depth were similar,in contrast with the trends of very fine sand and fine sand. The development history of channel could be divided into three stages according to the content changes of colloid,clay and fine silt. The profile at the 36,58,86,182 and 292 cm corresponded to rainfalls with strong erosion,among which,86 cm corresponded to the strongest rainfall. The mean grain size of the whole area showed sedimentary cycle change rule of ＂fine- coarse- fine＂. The sedimentary structure above 408 cm changed significantly and the dynamic environment was complex. Most of the grain size frequency curves were unimodal; the sorting of sediments was weak; the frequency curve presented positively skewed and very positively skewed; there were moderate and very narrow kurtosis. The deposition rate in Huangtuwa Area was higher in 1963 ~ 1986,slower in 1986 ~ 1994,and got faster after 1994.
出处
《山东农业科学》
2016年第5期67-74,共8页
Shandong Agricultural Sciences
基金
国家自然科学基金项目"陕北黄土高原典型小流域近500年来侵蚀产沙量变化研究"(41071012)
陕西能源开发水土保持动态监测管理系统开发研究(15H1000153)
关键词
黄土洼
淤地坝
沉积物
粒度特征
沉积环境
Huangtuwa
Check dam
Sediments
Grain size characteristics
Sedimentary environment
