Peak discharge increase in hyperconcentrated floods |
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| Institution: | 1. Geological Survey of Israel, Malkhe Israel St. 30, Jerusalem 95501 Israel;2. Recanati Institute for Maritime Studies and Leon H. Charney School of Marine Sciences, University of Haifa, Haifa 31905 Israel;1. CONICET - Laboratorio de Palinología y Bioantropología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250, CP (7600) Mar del Plata, Argentina;2. Laboratorio de Palinología y Bioantropología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250, Mar del Plata, Argentina;3. CONICET - Laboratorio de Paleoparasitología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250, Mar del Plata, Argentina;1. Department of Cardiology, Academic Medical Center, Amsterdam, The Netherlands;2. Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands;3. Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands;4. Department of Cardiology, Haga Hospital, The Hague, The Netherlands;5. Department of Cardiology, Leiden University Medical Center, The Netherlands |
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| Abstract: | The peak of river floods usually decreases in the downstream direction unless it is compensated by freshwater inflow from tributaries. In the Yellow River (China) the opposite is regularly observed, where the peak discharge of river floods increases in the downstream direction (at a rate far exceeding the contribution from tributaries). This flood peak discharge increase is probably related to rapid morphological changes, to a modified bed friction, or to a combination of both. Yet the relative role of these processes is still poorly understood. This paper aims to analyze the relative contribution of bed erosion and friction change to the peak discharge increase, based on available data and a recently developed numerical model. Using this high-resolution, fully coupled morphodynamic model of non-capacity sediment transport, two hyperconcentrated floods characterized by downstream peak discharge increase are numerically reproduced and analyzed in detail. The results reveal that although erosion effects may contribute to the downstream discharge increase (especially in case of extreme erosion), for most cases the increase must be mainly due to a reduction in bed friction during peak discharge conditions. Additionally, based on the concept of channel storage reduction, the effects of decreasing bed friction and (very strong) bed erosion can be integrated in explaining the peak discharge increase. |
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| Keywords: | Hyperconcentrated flood Downstream peak discharge increase Coupled morphological modeling Yellow River Bed friction reduction Sediment transport |
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