Erosion and natural revegetation associated with surface land drains in upland peatlands
Erosion and natural revegetation associated with surface land drains in upland peatlands
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DOI：
10.1002/esp.1476
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发表时间：
2007-09-01
影响因子：
3.3
通讯作者：
Bosanko, Nick R.
中科院分区：
文献类型：
--
作者：
Holden, Joseph;Gascoign, Michelle;Bosanko, Nick R.
露天排水沟是泥炭地最常用的排水技术，在世界各地都很常见。土地排水增加了排水密度，促进了坡面泥沙源与河流的耦合。它们可能是泥炭地溪流系统的细沉积物的主要来源，但泥炭地排水沉积物产生的数据很少。许多排水沟现在被人类筑坝，但一些自然植被。本文介绍了泥炭排水系统的侵蚀和自然植被恢复与坡度、排水面积和遮阳等变量的关系。本文还提供了从开放的排水沟、被泥炭坝阻塞的排水沟、未受干扰的子集水区和集水区出口的泥沙通量的测量比较。在< 4度的缓坡上经常发现排水沟的自然填充物。坡度< 2度的排水沟很少被侵蚀，而坡度为bb0 ~ 4度的排水沟很少被填满。在排水沟汇合处经常观察到缺口退缩。在排水管道已被切割或切割到下面的矿物基质的地方，排水管道的恢复是不常见的。下水道底部以泥炭为基础的地方，植被更加普遍。悬垂植被影响了排水层的植被恢复，为排水层提供了遮阳。遮阳小于60%的排水地板往往比遮阳60-90%的排水地板有更大的植被覆盖。然而，几乎完全遮蔽的排水沟（约90%）有最大的地面植被。完整的排水渠是调查流域内悬浮泥沙的主要来源，其中18个中心点3%的泥沙来自未堵塞的排水渠，这些排水渠排水了7个中心点3%的区域。尽管冬季降水总量不是最大的，但冬季对悬浮泥沙的产生比其他季节更重要。用泥炭块沿其长度间隔筑坝的排水沟产沙量非常低。即使是堵塞不好的排水沟，水仍然可以沿着排水沟的整个过程流动，其悬浮沉积物的产生也比没有堵塞的排水沟少54倍。版权所有(c) 2007约翰威利父子有限公司
Open cut drains are the most frequently used drainage technique in peatlands and are common throughout the world. Land drains increase the drainage density and promote enhanced coupling of hillslope sediment sources with streams. They may be major sources of fine sediment to peatland stream systems but data on drain sediment production in peatlands are rare. Many drains are now being dammed by humans, yet some revegetate naturally. This paper presents a survey of the erosion and natural revegetation of peat drains related to variables such as slope, drainage area and shading. The paper also provides measured comparison of sediment flux from open drains, drains that have been blocked by peat dams, undisturbed subcatchments, and the catchment outlet. Natural infilling of drains was often found to occur on gentle slopes < 4 degrees. Drains on slopes < 2 degrees were rarely eroded, while drains on slopes > 4 degrees were rarely infilled. Nick-point retreat at the confluence of drains was often observed. Revegetation of drains was uncommon where drains have been cut or incised into the underlying mineral substrate. Where the drain floor was peat-based, revegetation was much more common. Revegetation of drain floors was affected by overhanging vegetation, which provided shading. Drain floors with less than 60% shading tended to have a greater vegetation cover than drains with 60-90% shading. However, drains that were almost totally shaded (> 90%) had the greatest floor vegetation. The intact drains were found to be major sources of suspended sediment within the survey catchments, with 18 center dot 3% of the sediment originating from the unblocked drains which drained 7 center dot 3% of the area. The winter quarter of the year was more important than other seasons for producing suspended sediment, even though precipitation totals were not greatest during this period. Drains which had been dammed at intervals along their length using peat blocks had very low sediment yields. Even poorly dammed drains, where water could still flow along the full course of the drain, had 54 times less suspended sediment production than unblocked drains. Copyright (c) 2007 John Wiley & Sons, Ltd.