Size-selective characteristics of splash-detached sediments and their responses to related parameters on steep slopes in Chinese loessial region

Abstract Knowledge of the size-selective characteristics of splash-detached sediments can progress the understanding of splash and subsequent interrill wash erosion processes, as well as improve their modelling. Rainfall intensity (I) and slope gradient (S), as well as rainfall kinetic energy (KE), runoff depth ( h) and runoff velocity (v) have important effects on splash-detached sediment size. The objectives of this study were to explore the responses of the size-selective characteristics (expressed by mean weight diameter, MWD) of splash-detached sediments to I and S, and to identify the relationships of MWD of splash-detached sediments with KE,  h and v. Simulated rainfall experiments were conducted on clay loam under different rainfall intensities (0.7, 1.0, 1.5, 2.0, and 2.5 mm min−1) and slope gradients (7, 10, 15, 20, and 25°) at the simulated rainfall hall in Yangling, China in 2017. Results showed that the MWD was 72.74–164.17 μm for the splash-detached sediments, which was lower than that of the soil matrix (183.23 μm). MWD increased logarithmically with increasing S, and MWD first increased and then decreased with increasing I or KE parabolically. The relationship of MWD with I and S can be described by an exponential-power combination equation (MWD = 216 e-1.25I I1.81 S0.28, R2 = 0.88). MWD was negatively related to  h and positively related to v. Comprehensive response of MWD to KE,  h and v can be described by an exponential-power combination equation (MWD = 0.33 e-0.002KE KE1.18  h-0.20 v0.27, R2 = 0.85). These findings showed that splash-detached sediment size was significantly affected by I and S, as well as KE,  h and v. The study could be helpful in soil conservation management for similar conditions of soil, rainfall and land use.