草甸土冻融环境与春季解冻期降雨侵蚀模拟研究

以我国东北草甸土为研究对象,采用人工模拟降雨方法,分析试验区冻融环境及春季解冻期室外降雨侵蚀过程。结果表明:温度大体经历了降温、稳定和升温3个阶段,对应地表土壤经历了冻结、稳定冻结和融化3个过程;表层土壤在冻结和融化的两个过程中都经历了冻融作用,其中10月末至12月初和2月中下旬至3月上中旬均是地表土壤经受冻融交替作用强烈的时期,特别是融化阶段是控制春季解冻期土壤侵蚀的关键时期;冻融前后土壤含水率减小19%、土壤容重减小8.9%;整体土壤侵蚀速率表现为增加趋势;小雨强解冻深度浅的处理,侵蚀速率增加幅度不大,坡面细沟以宽浅型为主;大雨强侵蚀速率波动性增强。

Study on Freezing and Thawing Environment of Meadow Soil and Rainfall Erosion in Spring Thaw Period

Taking meadow soil in northeastern China as research object,freezing and thawing environment in the test region and the outdoor rainfall erosion process in the spring thaw period were analyzed.The results showed that: temperature generally experienced three stages of cooling,stability and warming,corresponding to the surface soil,it experienced three process of freezing,stable freezing and thawing;Surface soil both experienced freeze-thaw role in the process of freezing and thawing.Late October to early December and middle-late February to early-middle March were the strong period of alternate freezing and thawing effects of the surface soil,especially the melting stage was the critical period to control soil erosion in the spring thaw;after freezing and thawing,soil moisture content decreased by 19%,soil bulk density decreased by 8.9%;The overall soil erosion rates showed an increasing trend;when rainfall intensity was small and thaw depth was shallow,erosion rates increased marginally,slope rill mainly was wide-shallow rill;when rainfall intensity strong,rain erosion rate volatility increase.