Case study of a large summer flood on the North Slope of Alaska: bedload transport
Case study of a large summer flood on the North Slope of Alaska: bedload transport
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阿拉斯加北坡夏季大洪水案例研究：底土输送
DOI：
10.2166/nh.2008.006
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发表时间：
2008
影响因子：
2.7
通讯作者：
L. Hinzman
中科院分区：
文献类型：
--
作者：
J. McNamara;J. Oatley;D. Kane;L. Hinzman
融雪和降雨产生的洪水对北极河流沉积物运输的相对重要性在很大程度上是未知的，因为记录这两种事件类型的研究都很少见。2002年8月的一次降水事件在阿拉斯加库帕鲁克河上游产生了过去十年水文和地貌监测期间最大的流量（融雪或降雨），为记录北极河流对极端事件的地貌响应提供了机会。在本研究中，我们记录了地貌响应，并使用虚拟速度法估计了层质输运率。除了一些大于0.5米的随机巨石外，洪水几乎移动了整个河床。河道断面和水边调查数据表明，洪水产生了相当大的地貌响应。这种响应的强度导致示踪剂岩石采收率只有13%。据估计，通过研究剖面的总床质输运量为870立方米。河道形态，因此生境，是由大而不频繁的夏季降雨事件维持的。这些事件，特别是当它们发生在夏末几个月时，当活动层深度处于最大时，有可能产生比融雪径流事件多几个数量级的层载输送。然而，尚不清楚的是，融雪期间缺乏重要的床载运输是由于床载冰的保护，还是由于流量不足。
The relative importance of snowmelt versus rain-generated floods on sediment transport in arctic streams is largely unknown because studies documenting either event-type are rare. An August 2002 precipitation event produced the largest discharge level (snowmelt or rain) over the previous ten-year period of hydrologic and geomorphologic monitoring in the Upper Kuparuk River, Alaska providing an opportunity to document the geomorphologic response to of an arctic stream to an extreme event. in this study we document the geomorphologic response and estimate the bedload transport rate using the virtual velocity method. This flood mobilized virtually the entire bed, with the exception of random boulders greater than 0.5 m. The channel cross-section and water edge survey data illustrate the considerable morphologic response generated by the flood. The magnitude of this response resulted in only a 13% tracer rock recovery rate. The total bedload transport was estimated to be 870 m 3 of bed material through the study cross sections. Channel morphology, and therefore habitat, is maintained by large and infrequent summer rain events. These events, particularly when they occur in the late summer months, when active layer depth is at its greatest, have the potential to generate orders of magnitude more bedload transport than a snowmelt runoff event. It is unclear, however, if the lack of significant bedload transport during snowmelt is due to protection by bedfast ice or if flows are insufficient.