Effects of water erosion on wind erosion studied in rain simulator and wind tunnel on silty material taken from the Chernozem

Abstract

Composite erosion resulting from both water and wind poses a significant challenge to croplands in the Songnen Plain, located in northeast China, resulting in substantial soil degradation and loss of fertility. Nonetheless, the factors driving the effect of water erosion on wind erosion remain unclear. To address this, the study conducted controlled laboratory experiments that simulated conditions of rainfall and wind. Moreover, soil samples were exposed to rainfall intensities of 0, 50, and 100 mm h⁻¹, followed by wind tunnel tests with wind velocities of 9 m s⁻¹, 12 m s⁻¹, and 15 m s⁻¹. We subsequently assessed wind erosion characteristics and measured the soil properties of the residual surface soil in the trough. Our findings indicated that higher rainfall intensity significantly decreased the intensity of wind erosion by 42.3 %-85.5 % at 50 and 100 mm h⁻¹. Additionally, sediment transport height decreased by 4–10 cm across distinct rainfall intensities. Water erosion increased soil shear strength and compactness by 1.9 to 2.4 times and 2.8 to 4.8 times, respectively. Except for that, the clay content decreased by 14.2 %-39.2 % with different rainfall intensities and wind velocities. Moreover, the proportion of aggregates smaller than 0.25 mm decreased with increasing wind velocities. The contents of C, N, and CaCO₃ also diminished with higher wind velocity and rainfall intensity. Structural equation modeling analysis demonstrated that rainfall intensity indirectly influenced wind erosion intensity by altering soil properties. Meanwhile, rainfall intensity exhibited the strongest direct and indirect negative effects on sediment transport height. A nonlinear empirical equation for soil wind erodibility parameters (K) based on clay content was established, incorporating soil shear strength, CaCO₃ content, and rainfall intensity. This study offers a theoretical foundation for developing effective soil conservation strategies in the Songnen Plain.