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冻融作用对坡面侵蚀及泥沙颗粒分选的影响
引用本文:张 辉,李 鹏,鲁克新,任宗萍,王 添,汤珊珊,王飞超.冻融作用对坡面侵蚀及泥沙颗粒分选的影响[J].土壤学报,2017,54(4):836-843.
作者姓名:张 辉  李 鹏  鲁克新  任宗萍  王 添  汤珊珊  王飞超
作者单位:西安理工大学西北旱区生态水利工程国家重点实验室培育基地,西安,710048
基金项目:国家自然科学基金项目(41330858,41471226)、陕西省自然科学基础研究计划项目(2016JM4017)共同资助
摘    要:为了探究冻土和解冻土对水力侵蚀的影响,利用室内模拟降雨试验对冻土和解冻土两种坡面的坡面侵蚀过程及泥沙颗粒分选特征进行了研究。结果表明:在降雨条件下,相对于解冻坡面(TS),冻土坡面(FS)的产流时间提前了173s,而产流量、产沙量分别增加了9%和105%;两种坡面侵蚀过程中的土壤颗粒平均重量直径(MWD)大小次序均为溅蚀颗粒径流冲刷泥沙颗粒,且冻土坡面溅蚀颗粒及冲刷泥沙颗粒MWD均显著大于解冻土坡面(p0.05);随着降雨进行,解冻土坡面侵蚀泥沙中的黏粒、细粉粒含量呈先迅速增大后减少的趋势;粗粉粒和砂粒含量则呈先减小后增大的趋势,侵蚀泥沙逐渐向粗颗粒发展;而冻土坡面各粒级颗粒随时间变化相对稳定。研究成果可为进一步揭示冻融作用下坡面水力侵蚀机理提供一定的参考依据。

关 键 词:模拟降雨  冻土/解冻土  溅蚀  径流冲刷  颗粒分选
收稿时间:2016/6/9 0:00:00
修稿时间:2017/1/19 0:00:00

Effects of freezing and thawing on soil erosion and sediment particle size fractionation
ZHANG Hui,LI Peng,LU Kexin,REN Zongping,WANG Tian,TANG Shanshan and WANG Feichao.Effects of freezing and thawing on soil erosion and sediment particle size fractionation[J].Acta Pedologica Sinica,2017,54(4):836-843.
Authors:ZHANG Hui  LI Peng  LU Kexin  REN Zongping  WANG Tian  TANG Shanshan and WANG Feichao
Affiliation:Xi''an University of Technology,Xi''an University of Technology
Abstract:Objective] The Freezing-thawing action refers to daily,annual and secular climate change that might lead to freezing and thawing of the earth's surface in a certain climatic region.When the soil is frozen,soil water is frozen,too,thus expanding in volume and the expansion destroys the connectivity between soil particles,and hence change particle size distribution of soil particles.And during the thawing period,owing to the existence of both thawed soil layer and frozen soil layer at the same time,the soil differs sharply in erodibility from those completely frozen or thawed.However,studies focused mainly on changes in soil erodibility before and after freezing and thawing and gave little attention to studies on erodibility of frozen soils.Under the joint actions of hydraulic erosion and freezing-thawing erosion,the slope varies sharply in soil erosion and sediment particle size fractionation from those under the single action of hydraulic erosion,however,it is still unclear how soil erosion and sediment particle size fractionation varies under the joint actions.Method] Therefore,an indoor experiment was carried out using simulated rainfall to explore effects of freezing/thawing on water erosion during the thawing period on slopes of loess,processes of soil erosion on frozen and thawed slope and particle size fractionation of sediment.Result] Results show that affected by rain,runoff initiated 173 seconds earlier on the thawed slope than on the frozen one,while runoff rate and sediment yield was 9% and 105% higher,respectively.In terms of MWD of sediment particles generated during the processes of soil erosion on the two slopes,an order was observed as splash particles > scouring particles,but MWDs of the two types of particles were both significantly higher on frozen soil slopes than on thawed soil slopes (p < 0.05).During the erosion process with the rainfall going on,the contents of clay and fine silt increased first and then decreased,but the contents of coarse silt and sand did reversely,on the thawed slopes,while the sediment got dominated with coarse particles.However,particle size fractionation of the sediment on frozen slopes did not vary much with the time going on.Conclusion] On frozen slopes,the existence of an aquiclude aggravates the soil erosion,but during the hydraulic erosion process,the erosion was low in selectivity of sediment in particle size relative to that on thawed slope.This paper is expected to provide some valuable reference for better understanding the mechanism of soil erosion.
Keywords:Simulated rainfall  Frozen/thawed soil  Splash erosion  Runoff scouring  Particle size fractionation
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