典型黑土区坡耕地融雪、风力、降雨复合侵蚀效应

Compound erosion effect of snowmelt,wind,and rainfall on sloping farmlands of Chinese typical Mollisol region

研究多营力作用的坡耕地复合土壤侵蚀过程机理,可为精确防治农田土壤侵蚀提供科学指导。本研究基于东北黑土区坡耕地每年11月到次年10月冻融、融雪、风力、降雨侵蚀营力的季节性交替,利用不同侵蚀营力叠加的模拟试验,分析了坡耕地融雪(1、2 L·min^(-1))、风力(12 m·s^(-1))、降雨(100 mm·h^(-1))多营力叠加的复合侵蚀过程,讨论了各营力叠加的侵蚀效应。结果表明:仅融雪侵蚀下,坡面融雪径流量的增加对坡面侵蚀量的影响大于其对坡面径流量的影响;融雪径流量从1 L·min^(-1)增加到2 L·min^(-1),径流强度增加2.7倍,而侵蚀强度增加4.0倍。融雪-风力双营力叠加侵蚀下,前期融雪侵蚀对后期坡面风蚀有抑制作用,当融雪径流量从1 L·min^(-1)增加到2 L·min^(-1),融雪侵蚀对风蚀量的抑制作用增强,导致后期风蚀量减小50%以上。前期风力侵蚀和融雪-风力叠加侵蚀均加剧了后期坡面降雨侵蚀,前期风力侵蚀导致后期坡面降雨侵蚀量增加24.5%,融雪-风力叠加作用在1和2 L·min^(-1)融雪径流量下使后期坡面降雨侵蚀量分别增加132.8%和465.4%。多营力叠加的复合侵蚀量并非相应的单营力侵蚀量之和,还存在各营力叠加的促进或抑制效应。融雪-风力叠加的侵蚀效应为抑制效应,风力-降雨双营力叠加和融雪-风力-降雨多营力叠加的侵蚀效应为促进效应。

Research on the processes and mechanisms of compound soil erosion by multiple forces can provide scientific guidance for precisely controlling cropland soil erosion.Based on the seasonal alternation of freezing-thawing,snowmelt,wind,and rainfall erosion forces on sloping farmlands under natural conditions from November to next October of each year,we used a set of indoor simulation experiments of multi-force superimpositions to analyze the compound soil erosion processes of snowmelt(1 and 2 L·min^(-1)),wind(12 m·s^(-1)),and rainfall(100 mm.h^(-1)).We further discussed the erosion effects of multi-force superimpositions.The results showed that,under single snowmelt erosion,an increase in snowmelt flow had a greater effect on sloping snowmelt erosion intensity than that of sloping runoff rate.When sloping snowmelt flow increased from 1 L:min to 2 L·min^(-1),sloping runoff rate and erosion intensity increased by 2.7 and 4.0 times,respectively.Under snowmelt-wind superimposition erosion,previous sloping snowmelt erosion inhibited late wind erosion occurrence.As sloping snowmelt flow increased from 1 L·min^(-1)to 2 L min^(-1),the inhibiting action subsequently increased and wind erosion intensity caused by previous snowmelt reduced by more than 50%.Both wind erosion and snowmelt-wind superimposed erosion intensified late rainfall erosion.The early wind erosion increased rainfall erosion by 24.5%.The snowmelt-wind superimposed effect increased the later slope rainfall erosion by 132.8%and 465.4%under 1 and 2 L:minsn-owmelt runoff rates,respectively.The compound soil erosion amount driven by multiple force superimposition was not the sum of the corresponding erosion amount caused by single erosion force,with promoting or inhibiting effects of erosion force superimposition.The erosion effect of snowmelt-wind superposition was negative,but that of wind-rainfall superposition and snowmelt-wind-rainfall superpositions were positive.