Effects of Freeze-thaw Action on Snowmelt, Wind and Rainfall Erosion in Chinese Typical Mollisol Region

Abstract

[Objective] Researches on the effects of freeze-thaw action on slope soil erosion in the Chinese typical Mollisol Region can deepen the understanding of the mechanism of slope erosion process and provide important scientific basis for slope erosion control. [Methods] Using snowmelt, wind and rainfall erosion driven by a single erosion forces as controls, the effects of freeze-thaw on snowmelt, wind and rainfall erosion were analyzed by designing simulation experiments of freeze-thaw-snowmelt, freeze-thaw-wind and freeze-thaw-rainfall in the typical Mollisol Region of China. The experiment treatment consisted one freeze-thaw action, two snowmelt runoff flows (1 and 2 L/min), one wind velocity (12 m/s), one rainfall intensity (100 mm/h) and one slope (3°). [Results] (1) The freeze-thaw effect significantly increased the amount of slope snow melt, wind and rainfall erosion (p<0.05). Compared with no freeze-thaw action, the snowmelt erosion under 1,2 L/min snowmelt runoff increased by 2 042.9% and 777.9%, and the wind and rainfall erosion increased by 118.0% and 74.9%, respectively. (2) The effect of freeze-thaw on the process of water erosion (snowmelt and rainfall erosion) was greater than that on the process of runoff, and the process of slope erosion is aggravated, which increased the duration of active period and the intensity of slope erosion. The freeze-thaw action also increased the sediment transport height of wind erosion by 30%, and the sediment transport amount of wind erosion at each height increased by more than 50%. (3) The freeze-thaw action reduced soil erosion resistance, which significantly reduced surface soil bulk density, soil shear strength and soil hardness by 2.5%, 22.6% and 15.0%, respectively. At the same time, the freeze-thaw effect increased the average flow velocity 13.6%~25.0%, the shear force by 2.3%~81.9%, and the resistance coefficient by 1.6%~20.6%, thus aggravating the slope erosion process. [Conclusion] Freeze-thaw action changed the relationship between erosive dynamics and resistance, and intensified the process of snowmelt, wind and rainfall erosion on slope.

Keywords

• freeze-thaw action
• snowmelt erosion
• wind erosion
• rainfall erosion
• the chinese mollisol region