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

Abstract: [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 simulation of rainfall, with two rainfall intensities (40mm/h and 70mm/h) designed. Five rainfall events were conducted for each rainfall intensity 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, and new crust in the topsoil crust 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 5-2mm did not migrate in each rainfall, and the splashed agglomerates were mainly composed of particles with a size of 2-0.25mm, 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<0.053mm showed a trend of first decreasing and then increasing with the increase of intermittent frequency. The mass percentage with particle size<0.053mm 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 0.053mm. The research results provide reference for the study of soil water erosion mechanism in the black soil area of Northeast China.

Keywords: intermittent rain; Black soil; aggregate; erode