Characteristics of soil aggregates with different particle sizes and their quantitative relationship with slope erosion in rocky mountain area of northern China

ObjectiveThe purpose of this study is to clarify the structural characteristics of soil aggregates with different particle sizes (1-2 mm, 2-3 mm, 3-5 mm, 5-7 mm and 7-10 mm) and its impact on the process of interchannel and gully erosion.

MethodTwo kinds of typical cinnamon soil were selected as research objects. The stability of aggregates was analyzed by Le Bissonnais (LB) method and artificial rainfall test. The quantitative relations between stability characteristics of aggregates with different particle sizes and process of interchannel and gully erosion were studied.

ResultThe stability of limb drab soil aggregates was greater than loess brown soil, and the stability of aggregates with different particle sizes was significantly different. The stability of smaller size aggregates was larger than bigger size aggregates, among them, the aggregates with 1-2 mm particle size have the best stability. The difference of soil erosion under different rainfall intensities was obvious, the intensity of runoff and sediment of the slope increased with the increase of runoff duration, and the magnitude of rainfall intensity had a great effect on the changing rate of slope infiltration and the time to achieve a steady state of infiltration. Based on the WEPP gully and between channel erosion model framework, the erodibility, factor K_i was replaced by the modified characteristic parameter of aggregate stability K_a. By the analysis of regression, erosion prediction equations established with different particle sizes all showed good predictive performance, and the decision coefficients were above 0.81. Especially for the prediction equation corresponding to the particle size of 2-3 mm, the relative errors of between channel and gully were both less than 20%.

ConclusionThe study verifies that the stability of agglomerates with different particle sizes can be used as an indicator of soil erodibility. It establishes between channel and gully erosion prediction equations for aggregates of different sizes and provides a new idea for the study of the erosion mechanism of the brown soil in mountainous areas of northern China.