冻融作用对黑土坡面融雪、风力和降雨侵蚀的影响研究

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

[目的]研究冻融作用对东北黑土区坡面土壤侵蚀的影响,可加深对黑土坡面侵蚀过程机理的认识,并为区域侵蚀治理提供重要科学依据。[方法]以东北黑土区单一侵蚀营力驱动的融雪、风力和降雨侵蚀为对照,通过设计冻融-融雪、冻融-风力、冻融-降雨双侵蚀营力叠加的模拟试验,分析冻融作用对坡面融雪、风力和降雨侵蚀的影响。试验处理包括1次冻融作用、2个融雪径流量(1,2 L/min)、1个风速(12 m/s),1个降雨强度(100 mm/h)和1个坡度(3°)。[结果](1)冻融作用显著增加坡面融雪、风力和降雨侵蚀量(p<0.05)。与无冻融作用相比,1次冻融作用使坡面融雪侵蚀在1,2 L/min融雪径流下分别增加2042.9%和777.9%,使风蚀量和降雨侵蚀量分别增加118.0%和74.9%。(2)冻融作用对坡面水蚀(融雪和降雨侵蚀)过程的影响大于对径流过程的影响,且加剧坡面侵蚀过程,使坡面侵蚀活跃期历时增长和侵蚀强度增加;冻融作用也使风力侵蚀的输沙高度增加30%,各高度风蚀输沙量均增加50%以上。(3)冻融作用降低土壤抗侵蚀能力,其使表层土壤密度、土壤抗剪强度、土壤硬度分别显著减小2.5%,22.6%,15.0%。同时,冻融作用使水蚀过程中的坡面水流流速平均增加13.6%~25.0%,水流剪切力平均增加2.3%~81.9%,而阻力系数减小1.6%~20.6%,进而加剧坡面侵蚀过程。[结论]冻融作用改变侵蚀动力与阻力关系,加剧坡面融雪、风力和降雨侵蚀过程。

[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 2042.9%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.