侵蚀泥沙颗粒特征研究进展

Research Progress of the Particle-Size Characteristics of Eroded Sediments

侵蚀泥沙颗粒对深入理解和模拟泥沙及与之有关的化学污染物质输移至关重要。通过对国内外相关研究归纳整理、总结经验,重点围绕土壤水蚀的2个主要过程(细沟间和细沟侵蚀),对侵蚀泥沙颗粒输移形式、各级未分散颗粒的机械组成、不同粒径颗粒的富集规律和分选特征以及影响因素等进行综述与评价。纵观国内外的研究进展,侵蚀泥沙颗粒流失规律的研究已经较为全面和深入,取得了一些共识性成果:(1)未分散状态下的泥沙颗粒粒径分布更适合用来描述、模拟泥沙的输移行为和与之相关的营养污染物质迁移;(2)侵蚀泥沙粒径分布主要受降雨和径流能量的限制,能量小时,径流优先输移细颗粒,泥沙以细颗粒的富集为主;随着能量的逐渐增大,泥沙逐渐变粗;当能量足够大而产生细沟的时候,泥沙粒径分布趋向于接近原土;(3)团聚性好的土壤,其侵蚀泥沙粒径较团聚性差的土壤粗。

The particle-size characteristic of eroded sediments is important in understanding, characterizing and modeling the transport behavior of sediment and sediment-associated chemicals. The objective of this study was to provide references through summary and reorganization of relevant researches at home and abroad. This paper reviewed and evaluated the transport forms of eroded sediments, the primary particle-size composition of sediments undispersed with different size, the enrichment and selectivity of different size-class particles, and factors. Some results reached a consensus:(1) Undispersed sediment-size distribution is required for describing and modeling sediment transport and the associated movement of nutrients and contaminants.(2) This erosion selectivity, in fact, primarily results from the energy limitation of rainfall and runoff. When the energy is small, runoff is preferred to transport fine particles, and sediment is mainly enriched by fine particles. As the energy gradually increases, the sediments gradually thicken. When the energy is large enough to produce rill, the sediments size distribution tends to be close to the original soil.(3) The size distribution of sediments for the well-aggregated soils usually is much coarser than the less-aggregated one.