Impact of raindrop sizes and intensities on the microcharacteristics of
soil aggregates
Abstract
Aggregate breakdown caused by the impact of raindrops clogs soil pores,
reduces soil infiltration and aggravates the formation of soil crusts.
To determine the influence of raindrop splash on the microstructure of
soil aggregates, the typical loess was studied. We used
synchrotron-based X-ray microcomputed tomography (SR-μCT) to analyze the
microcharacteristics of soils impacted by rainfall intensities. The
results showed that raindrop splash increases the number of surface soil
aggregates, especially when the rainfall intensity is 68.61 or 217.26 mm
h-1. Compared to the undisturbed soil, the number of soil aggregates
increased by 38.71%, 46.77% and 76.77%, and the volume increased by
1.09%, 3.21% and 3.73%, after the impact of rainfall intensities of
5.76, 68.61 and 217.26 mm•h-1, respectively. Raindrop impact on the
surface affects the distribution of aggregate particles, causing a
decrease in the number of aggregate particles in the 500-1000 μm range
and an increase in the < 500 μm range. Compared with
unsplashed soil, there is a significant increase in the fractal
dimension (FD) and total specific surface area (SSA) of surface soil
aggregates in splashed soil. Particularly, the rainfall intensity of
217.26 mm h-1 resulted in an increase of the FD and SSA by 30.24% and
17.49%, respectively. Under the rainfall intensities, the average
particle diameter of the soil aggregates decreased by 2.43%, 3.25% and
3.55%, respectively, compared with that of the undisturbed soil. These
results indicated that raindrop splash decreased the number of
macroaggregates and increased the number of microaggregates in the
surface layer of soil.