A field investigation into the effects of progressive rainfall-induced soil seal and crust development on runoff and erosion rates: The impact of surface cover
A field investigation into the effects of progressive rainfall-induced soil seal and crust development on runoff and erosion rates: The impact of surface cover
复制标题
DOI：
10.1016/j.geomorph.2006.10.007
复制
发表时间：
2007-07
期刊：
影响因子：
3.9
通讯作者：
M. Neave;S. Rayburg
中科院分区：
文献类型：
--
作者：
M. Neave;S. Rayburg
地表结壳和海豹可由各种物理和生物过程形成，并有可能改变径流和侵蚀，特别是在植被覆盖率低的地区。尽管海豹和结壳之间有着明显的联系，但很少将这些特征放在一起考虑。本研究采用降雨模拟实验，调查细沟间土壤结壳和密封的发展，在结构（或雨滴影响引起的）和沉积（或径流引起的）过程中的半干旱皮埃蒙特在南部新墨西哥州，美国，经历了实质性的植被变化（灌木取代草）在过去的100年。研究设计包括六个双对径流小区分为四个子区，每个小区暴露于三个降雨模拟事件。这些地块上的地壳发展进行了评估，使用渗透阻力测量，而密封的发展进行了评估，使用径流系数。穿透阻力数据表明，直接暴露于雨滴影响的子地块（未覆盖地块）的结壳比位于网格覆盖物（覆盖地块）下方的结壳强40%，网格覆盖物可以拦截降雨的动能。每次模拟后，暴露于雨滴撞击的结壳强度增加，而覆盖表面的结壳在两次事件后达到一个平台。径流数据表明，海豹的发展并不直接反映地壳的形成。径流系数增加后，每个降雨模拟事件，但没有显着差异的覆盖和未覆盖的地块。相反，在土壤表面的石头滞后或凋落物的存在影响径流和密封发展之间的关系。未覆盖表面的产沙量超过覆盖表面的产沙量，这表明雨滴的影响有助于将沉积物输送到水流中。这项研究的结果表明，皮埃蒙特植被覆盖的丧失增加了表层地壳和海豹的发展程度，但这些地壳可能在减轻侵蚀方面发挥重要作用。
Surface crusts and seals can form from a variety of processes, both physical and biological, and have the potential to alter runoff and erosion, especially in regions with low vegetation covers. Despite the obvious links between seals and crusts these features have rarely been considered together. This study uses rainfall simulation experiments to investigate interrill soil crust and seal development in response to structural (or raindrop-impact-induced) and depositional (or runoff-induced) processes on a semiarid piedmont in southern New Mexico, USA, which has undergone substantive vegetation change (replacement of grasses by shrubs) over the last 100 years. The study design incorporates six double-paired runoff plots divided into four subplots, each of which was exposed to three rainfall simulation events. Crust development on these plots was assessed using penetration-resistance measurements while seal development was assessed using runoff coefficients. The penetration-resistance data indicate that subplots directly exposed to raindrop impacts (uncovered plots) have crusts that are ∼40% stronger than those positioned beneath a mesh cover (covered plots) that intercepts the kinetic energy of the rainfall. The crusts exposed to raindrop-impacts increased in strength following each simulation, whereas the crusts on the covered surfaces reached a plateau after two events. Runoff data indicate that seal development does not directly mirror crust formation. Runoff coefficients increased after each rainfall simulation event but were not significantly different between the covered and uncovered plots. Rather, the presence of stone lags or litter on the soil surface influenced the relation between runoff and seal development. Sediment yields from uncovered surfaces exceeded those from covered surfaces, indicating that raindrop impacts contribute to the delivery of sediment into flows. The results of this study indicate that the loss of vegetation cover on the piedmont has increased the extent of surface crust and seal development but that those crusts may be playing an important role in mitigating erosion.