7Be示踪坡耕地次降雨细沟与细沟间侵蚀

对于坡面细沟与细沟间侵蚀过程的了解是建立侵蚀预报模型的基础，但传统方法难以对其进行深入研究。利用7Be示踪技术并结合人工模拟降雨，考虑坡脚沉积作用，研究了25°坡耕地径流小区次降雨过程中细沟与细沟间侵蚀动态。结果表明：根据流出径流小区泥沙7Be含量变化计算坡面明显细沟出现时间，由于坡脚沉积作用使得A、B两试验小区这一时间比实际细沟出现分别延迟了45 min和11 min；根据坡面-侵蚀泥沙中7Be总量守恒和泥沙质量平衡原理，坡面细沟间侵蚀及细沟侵蚀在坡面总侵蚀、坡脚沉积区泥沙及流出径流小区泥沙中的比例被定量区分开；总体上，细沟间侵蚀量在径流泥沙中的比例逐渐减少，而细沟侵蚀量逐渐增加。两试验小区中7Be示踪计算坡面细沟侵蚀量和坡脚沉积量与实测值相比相对误差均较小，因此7Be示踪技术可以对土壤侵蚀进行较为准确地定量研究。

Interrill and rill erosion tracing on cultivated slopes using 7Be during individual rainfall event

Understanding the processes of interrill and rill erosion is necessary to develop soil erosion prediction models. However, it is difficult to obtain the information using traditional monitoring techniques. In the study, considering deposition at the base of slope area, 7Be was used as a tracer to describe the interrill and rill erosion dynamic during a simulated rainfall event in a slope farmland with a gradient of 25°. The results indicated that the appearance time of significant rill calculated by 7Be content of sediment exuded from the A and B plots was delayed for 45 min and 11 min respectively compared with actual time because of deposition at the base of slope area. Based on the mass balance of 7Be in the eroded soil and in the sediment and the balance of sediment mass, contributions of interrill and rill erosion were separately partitioned to the total soil loss, deposition at the base of slope area and sediment from the plots. In total, the contributions of interrill erosion to the sediment which was delivered out of plot gradually decreased temporally and rill erosion increased. In both plots, the relative errors between calculation values of rill erosion on slopes and deposition in the foot area using 7Be and measurement values of them were low. Therefore, 7Be tracer could accurately quantify the processes of soil erosion.