中文摘要：

侵蚀泥沙来源的研究对深化侵蚀规律的认识,优化水土保持措施的配置等有重要的意义。本文利用7Be示踪技术结合传统的土壤侵蚀研究方法,通过建立不同坡度的径流小区,分别探讨了坡耕地小区坡面不同坡段片蚀、细沟侵蚀对侵蚀泥沙的贡献率及小区泥沙输移比。研究发现,片蚀主要发生在小区坡面距坡顶0～2m区域,占总片蚀量的60%以上,细沟侵蚀主要发生在小区坡面距坡顶2～5m区域,占总细沟侵蚀总量的75%以上,总体而言,侵蚀泥沙主要来源于小区坡面距坡顶1～4m区域,上部和下部泥沙贡献相对较小。对于降雨强度高的15°小区,片蚀泥沙几乎来自与全坡面,坡面不同坡段对总侵蚀泥沙的贡献率从坡顶向坡脚呈增加趋势。利用^7Be示踪计算出各小区泥沙输移比在0.643～0.979之内,除5°小区外,其它小区泥沙输移比都大于0.9。

英文摘要：

The research of sediment source is significantly important for studying soil erosion and designing soil and water conservation measures on slopes.Combined with traditional methods,using 7Be measurement to document the contribution rate of sediment from different parts of the cultivated runoff plots is conducted in this paper.The sediment caused by sheet erosion was mainly derived from the part of 0-2m away from the slope top,accounting for over 60% of the total sheet erosion amount.The sediment caused by rill erosion was mainly derived from the lower-middle part of the plot slope（2-5m away from the slope top）,accounting for over 75% of the total rill erosion amount.The total eroded sediment was mostly derived from the middle-part of the plot slope（1-4m away from the slope top）.When the rainfall intensity was high,the sediment caused by sheet erosion was mostly derived from the entire plot（for example 15° plot）.The sediment contribution rate of the total erosion amount from the different parts of the 15° plot increased from the top to the base of the slope.It showed that the rainfall intensity was a significant factor for the erosion intensity distribution on the plot slope.According to the results of ^7Be measurement,the SDR of each plot was calculated during an event rainfall.The SDR of the plots varied between 0.643 and 0.979 and was close to 1 except the 5° runoff plot.