Coupling effects of erosion and surface roughness on colluvial deposits under continuous rainfall
Coupling effects of erosion and surface roughness on colluvial deposits under continuous rainfall
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DOI：
10.1016/j.still.2019.03.016
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发表时间：
2019-08
影响因子：
6.5
通讯作者：
Y. Liao;Zaijian Yuan;M. Zhuo;Bin Huang;X. Nie;Zhenyue Xie;C. Tang;Dingqiang Li
中科院分区：
文献类型：
--
作者：
Y. Liao;Zaijian Yuan;M. Zhuo;Bin Huang;X. Nie;Zhenyue Xie;C. Tang;Dingqiang Li
崩塌沟蚀形成的崩积物为随后的水蚀提供了大量的泥沙。以往的研究表明，降雨、径流和坡度对崩积物的侵蚀有明显的影响，但对土壤表面粗糙度的影响关注较少。本研究的目的是探讨在连续降雨条件下，地表粗糙度和侵蚀过程之间的关系。为此，我们在30°的崩积存款斜坡上重复了20次室内降雨实验。降雨强度为3.33 mm min− 1，降雨持续时间为60分钟。在降雨试验条件下，测量了各次降雨的产沙量和相关的水动力参数，包括流速、弗劳德数、雷诺数、径流功率和Darcy-Weisbach阻力系数。我们发现，粗颗粒和砾石在崩积物表面的逐渐富集导致产沙量呈指数下降。水蚀过程包括三个过程：（1）崩岗的出现，随后细沟的形成和迅速扩展;（2）细沟的频繁扩展;（3）细沟壁的随机滑坡。流速、弗劳德数（Fr）、雷诺数（Re）和径流功率（ω）均呈幂次减小趋势，而达西-韦斯巴赫阻力系数（f）则呈幂次增大趋势。粗糙度和流速可以作为表征崩积物水蚀强度的较好指标。研究结果将有助于进一步研究糙率对崩积物水蚀的影响。
The colluvial deposits, resulting from the collapsing gully erosion, provide a large amount of sediment for subsequent water erosion in southeastern China. Previous studies have shown the apparent effects of rainfall, runoff and slope gradient on erosion of colluvial deposits, but paid little attention to the effect of soil surface roughness. The objective of this study was to investigate the relationship between surface roughness and erosion processes under continuous rainfall conditions. For this purpose, we repeated an indoor rainfall experiment 20 times on a colluvial deposit slope of 30°. The rainfall intensity was 3.33 mm min−1and the rainfall lasted 60 min. We measured the sediment yield for each rainfall experiment and the related hydrodynamic parameters, including the flow velocity, Froude number, Reynolds number, Runoff power and Darcy-Weisbach resistance coefficient. We found that the gradual enrichment of coarse particles and gravel on the surface of the colluvial deposits led to an exponential decrease in sediment yield. The water erosion consists of three processes: (1) The emergence of the falling-sill, followed by the formation and rapid expansion of the rill; (2) The frequent expansion of the rill; and (3) The random landslide of the rill wall. The flow velocity, Froude number (Fr), Reynolds number (Re) and runoff power (ω) all showed a power decrease in contrast to a power increase of Darcy-Weisbach resistance coefficient (f) due to the influence of the roughness of colluvial deposits. The roughness and flow velocity can be used as good indicators for characterizing the water erosion intensity of the colluvial deposits. The findings will facilitate further research into the effect of roughness on the water erosion of colluvial deposits.