Prediction of flash flood hazard impact from Himalayan river profiles
Prediction of flash flood hazard impact from Himalayan river profiles
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DOI：
10.1002/2015gl063784
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发表时间：
2015-07
影响因子：
5.2
通讯作者：
R. Devrani;Vimal Singh;S. Mudd;Hugh D. Sinclair
中科院分区：
文献类型：
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作者：
R. Devrani;Vimal Singh;S. Mudd;Hugh D. Sinclair
我们在多大程度上可以将地形指标（如河流纵剖面）视为多个极端地貌事件的长期记录，从而将其用于灾害预测？我们证明，在一个地区的快速山地侵蚀的景观是高度反应的极端事件，通道陡度测量的整合面积超过上游距离（chi分析）可以被用来作为一个指标的地貌变化在山洪暴发。2013年6月，我们将归一化的河道陡度与印度北方北阿坎德恒河盆地上游的毁灭性洪水的影响进行了比较。沉积物积累和侵蚀的模式大致可从标准化的渠道陡度的分布预测;在高陡度河段，渠道降低到5米底切建筑物造成倒塌;在低陡度河段，渠道加积到30米，拓宽造成洪水和掩埋的沉积物。归一化的河道陡度提供了极端洪水事件期间地貌变化信号的一阶预测。低坡度河段的沉积物淤积是一种可预测的洪水特征，其流量的一部分由冰川湖等点源供给。
To what extent can we treat topographic metrics such as river long profiles as a long‐term record of multiple extreme geomorphic events and hence use them for hazard prediction? We demonstrate that in an area of rapid mountain erosion where the landscape is highly reactive to extreme events, channel steepness measured by integrating area over upstream distance (chi analysis) can be used as an indicator of geomorphic change during flash floods. We compare normalized channel steepness to the impact of devastating floods in the upper Ganga Basin in Uttarakhand, northern India, in June 2013. The pattern of sediment accumulation and erosion is broadly predictable from the distribution of normalized channel steepness; in reaches of high steepness, channel lowering up to 5 m undercut buildings causing collapse; in low steepness reaches, channels aggraded up to 30 m and widened causing flooding and burial by sediment. Normalized channel steepness provides a first‐order prediction of the signal of geomorphic change during extreme flood events. Sediment aggradation in lower gradient reaches is a predictable characteristic of floods with a proportion of discharge fed by point sources such as glacial lakes.