间歇性降雨条件下黑土溅蚀团聚体分选特征

Sorting Characteristics of Black Soil Splash Erosion Aggregates Under Intermittent Rainfall Conditions

[目的]为探究间歇性降雨对黑土溅蚀量和溅蚀分选特征的影响。[方法]基于人工模拟降雨试验,设计2个降雨强度(40,70 mm/h),每个降雨强度5场降雨,分析不同降雨条件下黑土溅蚀量和溅蚀团聚体粒径分布特征。[结果]2种降雨强度下,不同降雨场次土壤表层存在“无结皮-弱结皮-强结皮-弱结皮-新结皮”强弱交替的结皮动态发育过程。2种降雨强度下,溅蚀团聚体MWD和GMD均在第4场降雨出现最大值,在第1次降雨出现最小值。每场降雨5~2 mm粒级的团聚体均基本未发生迁移,溅蚀团聚体均以2~0.25 mm粒径为主,分别占2种降雨强度溅蚀量的36.49%~58.61%和49.10%~60.09%。5场降雨的溅蚀量随粒径减小呈先增加后减小的变化趋势,而粒径<0.053 mm质量百分数随间歇次数增加的变化趋势为先降低再增加,粒径<0.053 mm质量百分数均在第3场降雨出现最小值,分别为18.21%和17.63%。[结论]降雨导致土壤结皮的形成,且随降雨次数的增加结皮厚度呈现动态变化,在第3场降雨土壤结皮厚度最大,此时溅蚀量有最小值,且主要以>0.053 mm为主。研究结果为东北黑土区土壤水蚀机理研究提供参考。

[Objective]To investigate the impact of intermittent rainfall on the amount and sorting characteristics of black soil splash erosion.[Methods]This study is based on artificial simulated rainfall experiments,with two rainfall intensities(40,70 mm/h)designed,each with 5 rainfall events,to analyze the splashing erosion amount and particle size distribution characteristics of black soil under different rainfall conditions.[Results]Under two different rainfall intensities,there is a dynamic development process of alternating strength between"no crust weak crust strong crust weak crust new crust"in the soil surface layer of different rainfall sites.Under two different rainfall intensities,the maximum values of splashed aggregate MWD and GMD appeared in the fourth rainfall,and the minimum values appeared in the first rainfall.The agglomerates with a particle size of 5~2 mm did not migrate in each rainfall,and the splashed agglomerates were mainly composed of particles with a size of 2~0.25 mm,accounting for 36.49%~58.61%and 49.10%~60.09%of the splashed erosion amounts of the two rainfall intensities,respectively.The erosion amount of the five rainfall events showed a trend of first increasing and then decreasing with the decrease of particle size,while the mass percentage with particle size<0.053 mm showed a trend of first decreasing and then increasing with the increase of intermittent frequency.The mass percentage with particle size<0.053 mm all showed the minimum value in the third rainfall event,which was 18.21%and 17.63%,respectively.[Conclusion]Rainfall can lead to the formation of soil crust,and the thickness of soil crust shows dynamic changes with the increase of rainfall frequency.In the third rainfall,the soil crust thickness is the highest,and at this time,the splash erosion amount has the minimum value,mainly greater than 0.053 mm.The research results provide reference for the study of soil water erosion mechanism in the black soil area of Northeast China.