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Characteristics of sediment dynamics following large-scale sediment supply events in mountain watersheds in Japan
Geomorphology ( IF 3.1 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.geomorph.2020.107301
Hiroaki Izumiyama , Taro Uchida , Katsuya Horie , Wataru Sakurai

Abstract Large-scale sediment supply events (LSEs) cause not only a sudden increase in sediment discharge immediately after their occurrence, but also a long-term condition of elevated sediment yield. In Japan, many LSEs, triggered by heavy rainfall or earthquakes have created high risks for sediment-related disaster. However, the difference between sediment dynamics following a LSE triggered by rainfall and one triggered by an earthquake is unclear, as the sediment dynamics due to rainfall and those due to earthquakes have not been compared using consistent methodology. In this study, we estimated the volume of sediment supply VL (m3), time series of the volume of sediment yield VY (m3year−1) and the non-dimensional parameter NVY as estimated by dividing VL by the catchment area and annual maximum 3-day rainfall amount using the same methodology for 16 events in eight study basins in Japan. We used annual maximum 3-day rainfall amounts as a surrogate for discharge. Using these parameters, we estimated the period over which the effect of a LSE continues (PLS); sediment retention time (residence time, Tr1), and time for active sediment yield to recover to the background level (recovery time, Tr2a). In addition, we estimated the recovery time (Tr2b) based on when the maximum of NVY immediately after the LSE decreased to a certain extent. This calculation allowed us to estimate the recovery time even when background level was unknown. Both residence and recovery times ranged from

中文翻译:

日本山区流域大规模泥沙补给事件后泥沙动力学特征

摘要 大规模泥沙补给事件(LSEs)不仅会在发生后立即导致泥沙流量突然增加,而且会导致泥沙产量长期升高。在日本,许多由强降雨或地震引发的 LSE 为沉积物相关灾害带来了高风险。然而,降雨引发的 LSE 和地震引发的沉积物动力学之间的差异尚不清楚,因为尚未使用一致的方法比较降雨引起的沉积物动力学和地震引起的沉积物动力学。在本研究中,我们估算了沉积物供应量 VL (m3),沉积物产量 VY (m3year−1) 和无量纲参数 NVY 的时间序列,通过将 VL 除以集水区和年最大 3 天降雨量使用相同的方法对 8 个研究流域的 16 个事件进行估计日本。我们使用年度最大 3 天降雨量作为排放的替代值。使用这些参数,我们估计了 LSE 影响持续的时间段 (PLS);沉积物保留时间(停留时间,Tr1)和活性沉积物产量恢复到背景水平的时间(恢复时间,Tr2a)。此外,我们根据 LSE 后 NVY 的最大值何时下降到一定程度来估计恢复时间(Tr2b)。即使在背景水平未知的情况下,这种计算也使我们能够估计恢复时间。停留时间和恢复时间都从 我们估计了 LSE 影响持续的时间 (PLS);沉积物保留时间(停留时间,Tr1)和活性沉积物产量恢复到背景水平的时间(恢复时间,Tr2a)。此外,我们根据 LSE 后 NVY 的最大值何时下降到一定程度来估计恢复时间(Tr2b)。即使背景水平未知,这种计算也使我们能够估计恢复时间。停留时间和恢复时间都从 我们估计了 LSE 影响持续的时间 (PLS);沉积物保留时间(停留时间,Tr1)和活性沉积物产量恢复到背景水平的时间(恢复时间,Tr2a)。此外,我们根据 LSE 后 NVY 的最大值何时下降到一定程度来估计恢复时间(Tr2b)。即使在背景水平未知的情况下,这种计算也使我们能够估计恢复时间。停留时间和恢复时间都从 即使在背景水平未知的情况下,这种计算也使我们能够估计恢复时间。停留时间和恢复时间都从 即使在背景水平未知的情况下,这种计算也使我们能够估计恢复时间。停留时间和恢复时间都从
更新日期:2020-10-01
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