径流冲刷条件下冻融坡面产沙时空分布

Spatio-temporal Distribution of Slope Sediment Yield in Under the Condition of Freezing and Thawing

为确定冲刷条件下冻融坡面侵蚀产沙时空分布特征,利用稀土元素(REE)示踪技术,采用2个坡度(10°,15°),4个初始解冻深度(2,5,10,15cm),4个流量(4.5,6.5,8.5,10.5L/min)进行径流小区冲刷试验,分析冻融坡面侵蚀产沙时空变化规律。结果表明:相同初始解冻深度条件下土壤侵蚀产沙量随着坡度和流量的增大而增大,坡面第1坡段发生侵蚀最大,占总产沙量的68.24%,第3坡段产沙量一直趋于平稳状态;坡度相同时,侵蚀产沙量随着起始解冻深度和流量的增大而增大;冻融坡面侵蚀产沙量沿坡面方向和沿土壤深度方向逐渐降低;La元素示踪区产沙量随时间变化呈先增大后减小的趋势,其他各稀土元素示踪区产沙量随侵蚀时间变化的趋势与La元素示踪区产沙量的变化趋势基本一致。

In order to determine the temporal and spatial distribution of slope soil erosion and sediment yield under the condition of freeze-thaw cycle,rare earth element（REE）tracing technology was used in the study.Specifically,two gradients（10°,15°）,four initial thawing depths（2,5,10 and 15cm） and four water flows（4.5,6.5,8.5 and 10.5L/min）were designed to analysis the temporal and spatial variation of soil erosion and sediment yields.The results showed that the soil erosion and sediment yield increased with the increase of gradient and flow under the condition of the same initial thawing depth.The harvest soil erosion occurred in the first slope segment,which accounted for 68.24% of the total sediment yield,while the sediment yield was steady in third slope segment.The erosion and sediment yield increased with the increase of initial thawing depth and flow under the same slope gradient.The erosion and sediment yield reduced gradually with the slope and soil depth directions in freeze-thaw slope;In the La element tracer area,the sediment yield increased firstly, and then decreased,in other element tracer areas,the change of sediment yield was basically consistent with that of the La element tracer area.