Inferring bedload transport from stratigraphic successions: examples from Cenozoic and Pleistocene rivers, south central Pyrenees, Spain
Inferring bedload transport from stratigraphic successions: examples from Cenozoic and Pleistocene rivers, south central Pyrenees, Spain
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从地层序列推断底泥输送：西班牙比利牛斯山脉中南部新生代和更新世河流的例子
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
L. Frostick
中科院分区：
文献类型：
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作者：
S. Jones;L. Frostick
砾石河床的推移质输沙率一直是地质学家和地貌学家所关心的问题，特别是由于输沙率是控制河流冲淤和下切的重要因素。全新世河流的推移质输移方程在现代砾石河床系统中得到了广泛的应用。然而，古水力重建受到的关注较少，通常被认为是不准确的，因为大多数估计至少是一个数量级。本研究的重点是推导流功率，推移质输运率和效率估计渐新世-中新世和上新世-更新世砾石床河流沉积物从南部中央比利牛斯山脉，西班牙。在古水力计算中使用的基本数据是古坡度、古速度、古深度和砾石坝上每年洪水事件中堆积的沉积物体积的估计。从这些古老的河流系统的数据分析产生更准确的相对流功率，推移质输沙率和效率参数的估计。这项研究说明了需要了解河流系统的古水力学，以表征古代河流。具有低泥沙供给和高推移质输运率的砾石河床河流切割。相反，当泥沙供应充足时，推移质输移率和效率较低，河流系统会发生淤积。
Abstract Geologists and geomorphologists have long been concerned with rates of sediment transfer as bedload in gravel-bed rivers, especially as rates of sediment transfer are important factors controlling river aggradation and incision. Bedload transport equations, originally derived for Holocene streams, have been used widely in modern gravel-bed river systems. However, palaeohydraulic reconstructions have received less attention and are generally dismissed as inaccurate since most are estimated to be at least an order of magnitude out. This study focuses on deriving stream power, bedload transport rates and efficiency estimates for Oligo–Miocene and Plio–Pleistocene gravel-bed river deposits from the south central Pyrenees, Spain. The basic data used in the palaeohydraulic calculations are estimates of palaeoslope, palaeovelocity, palaeodepth and the volume of sediment accreted in yearly flood events on gravel bars. Analyses of data from these ancient river systems yield more accurate estimates of relative stream power, bedload transport rates and efficiency parameters. This study illustrates the need for understanding the palaeohydraulics of river systems in order to characterize ancient rivers. Gravel-bed rivers with low sediment supply and high bedload transport rates incise. Conversely, when sediment supply is abundant, bedload transport rates and efficiency are low and the river system aggrades.