Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Roxby Building, Liverpool, L69 7ZT, UK.
Sci Rep. 2019 Feb 8;9(1):1686. doi: 10.1038/s41598-019-38537-3.
A flash flood on 28th September, 2012, rose to a peak discharge of 2357 m s from zero within one hour in the ephemeral Nogalte channel in SE Spain. Channel morphology and sediment sizes were measured at existing monitored sites before and after the flood and peak flow hydraulics calculated from surveyed floodmarks and cross-sections. Maximum peak sediment fluxes were calculated as ~600 kg s m, exceeding maximum published, measured dryland channel values by 10 times and common perennial stream fluxes by 100 times. These high fluxes fit the established simple bedload flux - shear stress relations for dryland channels very well, but now extended over a much wider data range. The high sediment fluxes are corroborated by deposits at >1 m height in a channel-side tank, with 90 mm diameter sediment carried in suspension, by transport of large blocks and by massive net aggradation as extensive, structureless channel bars. Very high sediment supply and rapid hydrograph rise and recession produced the conditions for these exceptional sediment dynamics. The results demonstrate the extreme sediment loads that may occur in dryland flash floods and have major implications for catchment and channel management.
2012 年 9 月 28 日，西班牙东南部的诺加尔特（Nogalte）短暂性河道在一小时内洪峰流量从 0 上升到 2357 立方米每秒。洪水前后，在现有监测点测量了河道形态和沉积物粒径，并根据测量的洪水痕迹和横断面计算了峰值水流水力学。最大峰值泥沙通量约为 600 公斤每秒每米，是已发表的、测量的旱地河道最大干沙通量的 10 倍，是常见的常年溪流通量的 100 倍。这些高通量非常符合旱地河道的床沙质推移质通量-剪切应力关系，且数据范围更广。高泥沙通量在河道一侧的一个高 1 米以上的水箱中得到证实，其中悬浮着 90 毫米直径的泥沙，大石块被搬运，以及广泛的无结构的渠化沙洲的大量净淤积。非常高的泥沙供应以及快速的水位上升和下降为这些特殊的泥沙动力学创造了条件。研究结果表明，旱地洪水可能会产生极端的泥沙负荷，这对集水区和河道管理具有重大影响。
