Effects of herbaceous vegetation coverage and rainfall intensity on splash characteristics in northern China

The splash erosion characteristics of the herbaceous-dominant area in northern China remain uncertain. A total of 21 plots (3-m wide x 3-m long) were installed to investigate splash characteristics under different vegetation coverages (0%, 5%, 10%, 20%, 40%, 60%, and 80%) and rainfall intensities (40, 80, and 120 mm/h) using an artificial simulated rainfall device and an improved splash tray. Splashed particles were collected and analyzed for mass and size distribution. This study demonstrated that a vegetation coverage of 40% would help protect soil from splash erosion. Total splash amount generally decreased exponentially with increasing vegetation coverage and splash distance, but rose with increasing rainfall intensity. Vegetation coverage played a more important role in the mass-weighted average splash distance, with a significant Pearson correlation of -0.934 (p (<) 0.01), compared to the rainfall intensity, with no significant correlation (p > 0.05). Moreover, splashed particles were finer than the original soil matrix because finer soil particles (clay, fine silt, and coarse silt) were transported preferentially by raindrops, and almost all mean weight diameters were lower than that of the soil matrix. Coarse silt showed the largest mass percentage at all splashed distances relative to the least mass percentage of coarse sand. The mass percentages of clay, fine silt, and coarse silt were generally positively correlated with vegetation coverage and splash distance and negatively correlated with rainfall intensity (p (<) 0.05). Furthermore, the opposite was true for fine and coarse sand (p (<) 0.05). These results could facilitate the further understanding of splash erosion characteristics and provide some suggestions for erosion control practices in northern China where herbaceous plants are important ingredients.