Raindrop‐induced saltation and the enrichment of sediment discharged from sheet and interrill erosion areas
Raindrop‐induced saltation and the enrichment of sediment discharged from sheet and interrill erosion areas
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DOI：
10.1002/hyp.8270
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发表时间：
2012-05
影响因子：
3.2
通讯作者：
P. Kinnell
中科院分区：
文献类型：
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作者：
P. Kinnell
片状和细沟间侵蚀区是富含养分和污染物的土壤物质的来源。这些地区的土壤、养分和其他化学物质的流失在维持土壤生产力和场外环境健康方面都是一个令人担忧的问题。许多降雨侵蚀实验表明，片状和细沟间侵蚀区排出的沉积物中含有丰富的细微物质、营养物质和其他化学物质，但这些结果往往是在很短的时间内获得的。用一个雨滴引起的跃移的定性力学模型来说明这一输移机制如何影响受雨水冲击的水流排出的泥沙组成。最初，快速移动的颗粒在泥沙流量中得到丰富，但随着时间的推移，在降雨事件期间，移动较慢的颗粒变得更具代表性。雨滴引起的跳跃促进了物质在土壤表面的储存，其组成比原始土壤更粗糙。在高强度事件期间，通过发展流动驱动的跃变来筛选来自这个储存库的物质，可以改变后来由雨滴诱导的跃变所排放的沉积物的组成。在给定稳定的土壤颗粒的情况下，稳定状态下排出的泥沙的成分与原始土壤相同。浓缩是一种非稳态现象，如果不能认识到浓缩的瞬变性质，可能会对短期实验结果的含义作出不恰当的解释。版权所有©2011 John Wiley&Sons，Ltd.
Sheet and interrill erosion areas are sources of soil material rich in nutrients and pollutants. The loss of soil, nutrients and other chemicals from these areas is a matter of concern both in terms of maintaining soil productivity and the health of offsite environments. Many experiments on rainfall erosion have shown enrichment of fine material, nutrients and other chemicals in the sediment discharged for sheet and interrill erosion areas, but often these results were obtained over short periods of time. A qualitative mechanistic model of raindrop‐induced saltation is used to illustrate how this transport mechanism influences the composition of sediment discharged by rain‐impacted flow. Initially, fast moving particles are enriched in the sediment discharge but, over time, during a rainfall event, slower moving particles become more represented. Raindrop‐induced saltation promotes the storage of material on the soil surface with a coarser composition than the original soil. Winnowing of material from this storage by the development of flow‐driven saltation during high‐intensity events can modify the composition of the sediment discharged later by raindrop‐induced saltation. Given stable soil particles, the composition of the sediment discharged at the steady state is the same as the original soil. Enrichment is a non‐steady‐state phenomenon and failure to recognize the transient nature of enrichment may lead to inappropriate interpretation of the implications of the results from short‐term experiments. Copyright © 2011 John Wiley & Sons, Ltd.