Rainfall kinetic energy controlling erosion processes and sediment sorting on steep hillslopes: A case study of clay loam soil from the Loess Plateau, China
Rainfall kinetic energy controlling erosion processes and sediment sorting on steep hillslopes: A case study of clay loam soil from the Loess Plateau, China
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降雨动能控制陡坡侵蚀过程和沉积物分选：以中国黄土高原粘壤土为例
DOI：
10.1016/j.jhydrol.2014.02.066
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发表时间：
2014-05
影响因子：
6.4
通讯作者：
Zhang, H. Y.
中科院分区：
文献类型：
--
作者：
Wang, J.;Fang, N. F.;Wu, G. L.;Zhang, H. Y.
降雨动能（KE）可以分解土壤表面的团聚体。更好地了解与各种 KE 相关的沉积物分类对于土壤侵蚀模型的开发和验证至关重要。实验中使用粘壤土。通过在土壤表面上方覆盖不同孔径的丝网来改变落在土壤表面的雨滴的大小，同时保持相同的降雨强度（90 ± 3.5 mm h−1），获得了 6 个 KE（76、90、105、160、270 和 518 J m−2h−1）。对于每次降雨模拟，每隔 3 分钟收集一次径流和沉积物，以研究沉积物粒径分布 (PSD) 的时间变化。沉积物有效 PSD（未分散）和最终 PSD（分散）的比较用于研究沉积物动员中涉及的分离和传输机制。粘土尺寸颗粒的有效-最终比小于1，而沙尺寸颗粒的有效-最终比大于1，表明这些颗粒作为聚集体进行运输。在较高的 KE 下，有效-最终比率更接近 1，这表明由于粘壤土团聚体解聚的严重程度增加，沉积物在较高 KE 下更有可能作为初级颗粒进行迁移。当 KE 大于 105 J m−2h−1 时，粘土尺寸颗粒的百分比和悬浮盐化的相对重要性随着 KE 的增加而增加，而当 KE 小于 105 J m−2h−1 时，随着 KE 的增加而减少。 105 J m−2h−1 的 KE 似乎是一个阈值水平，超过该阈值，骨料的崩解会严重，并且 KE 对侵蚀过程和沉积物分选的影响可能会发生变化。这项研究的结果表明，在预测侵蚀时需要考虑 KE 影响的沉积物迁移。
Rainfall kinetic energy (KE) can break down aggregates in the soil surface. A better understanding of sediment sorting associated with various KEs is essential for the development and verification of soil erosion models. A clay loam soil was used in the experiments. Six KEs were obtained (76, 90, 105, 160, 270, and 518 J m−2h−1) by covering wire screens located above the soil surface with different apertures to change the size of raindrops falling on the soil surface, while maintaining the same rainfall intensity (90 ± 3.5 mm h−1). For each rainfall simulation, runoff and sediment were collected at 3-min intervals to investigate the temporal variation of the sediment particle size distribution (PSD). Comparison of the sediment effective PSD (undispersed) and ultimate PSD (dispersed) was used to investigate the detachment and transport mechanisms involved in sediment mobilization. The effective–ultimate ratios of clay-sized particles were less than 1, whereas that of sand-sized particles were greater than 1, suggesting that these particles were transported as aggregates. Under higher KE, the effective–ultimate ratios were much closer to 1, indicating that sediments were more likely transported as primary particles at higher KE owing to an increased severity of aggregate disaggregation for the clay loam soil. The percentage of clay-sized particles and the relative importance of suspension–saltation increased with increasing KE when KE was greater than 105 J m−2h−1, while decreased with increasing KE when KE was less than 105 J m−2h−1. A KE of 105 J m−2h−1appeared to be a threshold level beyond which the disintegration of aggregates was severe and the influence of KE on erosion processes and sediment sorting may change. Results of this study demonstrate the need for considering KE-influenced sediment transport when predicting erosion.
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