Impact of Initial Soil Moisture and Rainfall Energy on Splash Erosion Characteristics of Black Soil Aggregate

Abstract

[Objective] To investigate the influence of rainfall energy and initial moisture content on the mechanism of soil aggregate splashing erosion. [Methods] The typical cultivated black soil in northeast China was selected as the research object. Artificial simulated rainfall experiments were conducted to explore the splashing erosion characteristics of soil aggregates with varying initial moisture content, rainfall energy, and initial particle size of aggregates. [Results] (1) The splash erosion of the four kinds of black soil aggregates with initial particle size was highest when the initial soil moisture level was 4%, and the splash erosion of the aggregates with an initial particle size <0.25 mm was 1.21 to 5.50 times that of the aggregates with different particle sizes under the same rainfall energy conditions. Furthermore, as the initial soil moisture increased, the splash erosion of the aggregates within each particle size group decreased initially, but increased when the initial soil moisture surpassed 25%. (2) The splash erosion of four initial particle size black soil aggregates increased with the increase of higher rainfall energy. When the rainfall energy reached 909 J/(m2·h) (equivalent to 5 m), the splash erosion of the different-sized black soil aggregates increased by 15.37 to 20.70 (<0.25 mm), 52.30 to 417.60 times (0.25～1 mm), 51.58～359.36 times (1～3 mm), 68.73～777.99 times (3～5 mm), respectively. Notably, a clear threshold was observed for splash erosion of aggregates with different initial particle size. When the rainfall energy exceeded 529 J/(m2·h) (equivalent to 2 m), there was a significant difference in splash erosion among different rainfall energy gradient. (3) The analysis highlighted that rainfall energy was the primary factor affecting splash erosion. It exhibited a direct effect with a correlation coefficient of 0.811, demonstrating a significant positive influence. Conversely, the direct effects of initial soil moisture and initial particle size of aggregates were significantly negative, with correlation coefficients of 0.193 and 0.352, respectively. [Conclusion] The research findings can provide a scientific basis for investigating the mechanisms of slope soil erosion in the black soil regions of Northeast China, as well as for establishing process-based models for soil erosion.

Keywords

• initial soil moisture
• rainfall kinetic energy
• splash erosion
• the typical black soil region