Impact of Raindrop Characteristics on the Selective Detachment and Transport of Aggregate Fragments in the Loess Plateau of China.

Soil aggregate breakdown and detachment due to raindrop splash cause crusting and interrill erosion. Although raindrop splash can cause the aggregate breakdown, this fundamental processes associated with the size of splashed raindrops and their distance interval remain unresolved. To determine the relations between splash raindrop size/distance and the soil aggregate detachment/transport in the Loess Plateau of China, simulated rainfalls were created by a self-designed raindrop generation device for six raindrop sizes (raindrop diameter, 2.67-5.45 mm) and five splash distances (range, 0-10 cm to 40-50 cm). The results showed that the relationship between the amount of splash detachment and the raindrop size increased in a positive linear trend (P < 0.05) and that the relationship between the amount of splash detachment and raindrop size was a significantly decreased exponential function (P < 0.05). A model was obtained to predict the amounts of splash detachment (M) for the raindrop sizes (D) and distance of splash detachment (S): M = 0.741D4.846 S-1.820 (P < 0.05; r2=0.916). The size of the raindrop in a rainfall event was the direct driving force for the aggregate breakdown and dispersion: the greater the diameter of raindrops, the higher was the degree of aggregate breakdown and dispersion. The splash erosion for the aggregate fragment <0.053 mm was at a maximum with increases in raindrop diameter, which accounted for 33.46 to 72.02% of the total splash amount. The contents of microaggregate fragments of <0.25 mm were highest at each splash distance and accounted for 50.49 to 94.04% of the total splash amount. This showed that microaggregate dispersion and breakdown is important in soil surface sealing and pore clogging. [ABSTRACT FROM AUTHOR]