题目 Title

Suspended Sediment Pulses and Sediment-Discharge Relationships in Earthquake-Affected Rivers Along the Tibetan Plateau Margins

期刊 Journal

Water Resources Research (IF=6)

作者 Author

Zhou, Y.; Huang, L.; Wang, R.; Hu, M. Y.; Singh, V. P.; Fang, H. W.

摘要 Abstract

Large earthquakes along the Tibetan Plateau margins trigger widespread landslides that deliver substantial sediment to river networks, driving intense and long-lasting landscape change. However, identifying and modeling the fluvial sediment responses to large earthquakes remains challenging. In this study, we develop an earthquake-affected sediment transport model that couples fluvial transport with time-varying sediment supply, using multi-year time series of suspended sediment concentration (SSC) and flow discharge (Q) from three rivers affected by the 2008 Mw 7.9 Wenchuan, 2017 Mw 6.4 Nyingchi, and 2017 Mw 6.5 Jiuzhaigou earthquakes. The model represents enhanced sediment supply by seismic landslide inputs and rainfall-driven mass movement, and fluvial transport by Q-based transport capacity and channel sediment scouring and deposition. The results show that incorporating dynamic supply terms is indispensable to reproduce post-seismic SSC pulses and complex SSC–Q hysteresis. The proposed model explains 78%–90% of long-term SSC variance and outperforms traditional rating-curve approaches by 7%–74%. The model framework may have particular relevance for understanding the role of large, long-lasting seismic landslides in regulating post-seismic sediment regimes for other earthquake-affected regions.

简介 Brief introduction

青藏高原边缘地带的强震会引发广泛分布的滑坡，向河流网络输送大量泥沙，从而驱动强烈且长期的地貌演变。然而，识别并模拟河流泥沙对强震的响应仍具有挑战性。本研究构建了一个地震影响下的泥沙输运模型，该模型将河流输运过程与随时间变化的泥沙供给动态耦合；模型数据源自分别受2008年汶川地震（Mw 7.9）、2017年林芝地震（Mw 6.4）及2017年九寨沟地震（Mw 6.5）影响的三条河流，涵盖了多年的悬浮泥沙浓度（SSC）与流量（Q）时间序列数据。该模型通过地震滑坡输入及降雨驱动的物质搬运过程来表征泥沙供给的增强，并通过基于流量（Q）的输沙能力及河道泥沙冲刷与淤积过程来表征河流的泥沙输运。结果表明，引入动态泥沙供给项对于重现震后悬浮泥沙浓度（SSC）的脉冲式激增现象以及复杂的SSC-Q滞回曲线特征是不可或缺的。该模型能够解释长期悬浮泥沙浓度变异的78%-90%，且相比传统的“定级曲线法”（rating-curve approaches）提升了7%-74%。该模型框架对于理解大型、长期持续的地震滑坡如何调控震后泥沙输运格局具有重要的理论与实践意义，并可为其他受地震影响区域提供参考。

扫码关注立方体公众号，实时追踪课题组最新科研进展