Efficacy of bedrock erosion by subglacial water flow
Efficacy of bedrock erosion by subglacial water flow
复制标题
冰下水流侵蚀基岩的功效
DOI：
10.5194/esurf-4-125-2016
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发表时间：
2015
影响因子：
--
通讯作者：
J. Venditti
中科院分区：
文献类型：
--
作者：
F. Beaud;G. Flowers;J. Venditti
抽象的。基岩侵蚀沉积物的冰下水仍然很少研究，但是，该过程被认为有助于基岩侵蚀率在冰川景观，并牵连在隧道山谷的挖掘和内峡谷的切口。我们适应物理为基础的模型河流磨蚀冰下环境，组装的第一个模型，旨在量化基岩侵蚀所造成的瞬态冰下水流。冰下排水模型由一个一维网络的空腔动态耦合到一个或多个Rothlisberger通道（R通道）。基岩侵蚀模型是基于工具和覆盖效应，其中颗粒夹带的流动影响暴露的基岩。我们探讨冰川融水侵蚀的结构和规模的水输入系统，冰的几何形状和沉积物供应的依赖。我们发现，侵蚀是不是一个功能的水流量单独，但也取决于渠道的大小，水的压力，和沉积物供应，在河流系统。模拟的冰川融水侵蚀率是1至2个数量级低于预期的总冰川侵蚀所需的沉积物供应率，我们施加，这表明冰川融水侵蚀是可以忽略不计的流域规模。然而，由于冰川融水侵蚀的极端局部化（在R通道的底部），这个过程可以雕刻基岩（奈）通道。事实上，我们的模拟表明，几厘米深、几米宽的基岩通道的切割可以在一年内发生。模拟切割率表明，冰下水流可以逐渐雕刻隧道谷，并提高救济，甚至开始雕刻内峡谷。
Abstract. Bedrock erosion by sediment-bearing subglacial water remains little-studied; however, the process is thought to contribute to bedrock erosion rates in glaciated landscapes and is implicated in the excavation of tunnel valleys and the incision of inner gorges. We adapt physics-based models of fluvial abrasion to the subglacial environment, assembling the first model designed to quantify bedrock erosion caused by transient subglacial water flow. The subglacial drainage model consists of a one-dimensional network of cavities dynamically coupled to one or several Rothlisberger channels (R-channels). The bedrock erosion model is based on the tools and cover effect, whereby particles entrained by the flow impact exposed bedrock. We explore the dependency of glacial meltwater erosion on the structure and magnitude of water input to the system, the ice geometry, and the sediment supply. We find that erosion is not a function of water discharge alone, but also depends on channel size, water pressure, and sediment supply, as in fluvial systems. Modelled glacial meltwater erosion rates are 1 to 2 orders of magnitude lower than the expected rates of total glacial erosion required to produce the sediment supply rates we impose, suggesting that glacial meltwater erosion is negligible at the basin scale. Nevertheless, due to the extreme localization of glacial meltwater erosion (at the base of R-channels), this process can carve bedrock (Nye) channels. In fact, our simulations suggest that the incision of bedrock channels several centimetres deep and a few metres wide can occur in a single year. Modelled incision rates indicate that subglacial water flow can gradually carve a tunnel valley and enhance the relief or even initiate the carving of an inner gorge.
广阔的冰下融水通道表明前南极洲西部是温带冰盖
影响因子：
5.8
作者：
Rose K
通讯作者：
Rose K