近日，美国加州大学圣巴巴拉分校Gen K. Li团队研究了地震后持续十年的大河床沉积物通量。该项研究成果发表在2025年8月13日出版的《自然》杂志上。

大地震引起广泛的山体滑坡，泥沙填满河道，产生长期的河流灾害，重塑山区地形。然而，地震后的河流沉积物通量仍然没有得到很好的解决，这主要是因为缺乏关于河床通量的数据。

研究组构建了2008年Mw7.9级（其中Mw为矩震级）汶川地震后藏东地区的泥沙收支。他们测量了地震灾区下游一个人工水库的沉积量。地震发生10年后，岷江输沙量约占地震滑坡输沙量的9%，同期河流输沙量增加约5.7倍。与地震前相比，河床通量增加了{27.4}{-15.6}^{+14.6}%，占地震后沉积物输出的6亿{-26}^{+12}%，这一比例远高于大多数山地河流的典型水平。按照目前的速度，河流系统将在一百年的时间尺度上清除汶川滑坡的大部分碎片。

然而，由于山坡（例如植被）以及水文、沉积物特征和运输过程的变化，未来的沉积物输出率可能会有所不同。该发现证明了由地震引发的滑坡驱动的以床层为主导的沉积物脉冲，这表明在大地震发生后，人口稠密的下游地区对诸如恶化和洪水等级联灾害的脆弱性增加可能会持续数十年。

附：英文原文

Title: Large riverbed sediment flux sustained for a decade after an earthquake

Author: Li, Gen K., West, A. Joshua, Jin, Zhangdong, Qiu, Hongrui, Zhang, Fei, Wang, Jin, Hammond, Douglas E., Densmore, Alexander L., Hilton, Robert G., Dong, Sijia, Atwood, Abra, Fischer, Woodward W., Lamb, Michael P.

Issue&Volume: 2025-08-13

Abstract: Large earthquakes induce widespread landslides that fill river channels with sediment1,2, generating long-lasting fluvial hazards and reshaping mountain topography. However, riverine sediment fluxes after earthquakes remain poorly resolved, mostly because of a lack of data on bedload flux3,4. Here we construct a source-to-sink sediment budget following the 2008 Mw7.9 (where Mw is the moment magnitude) Wenchuan earthquake in the eastern Tibetan mountains. We measured sediment accumulation in a man-made reservoir downstream of the earthquake-affected region. Ten years after the earthquake, the Min Jiang River had exported about 9% of the sediment mass from earthquake-triggered landslides, with around 5.7 times increase in the total riverine sediment flux sustained over that time. Bedload flux increased by {27.4}_{-15.6}^{+14.6} % times compared with pre-earthquake levels, making up 6{5}_{-26}^{+12} % of the post-earthquake sediment export—a proportion much higher than typical of most mountainous rivers. At the current pace, the river system will remove most Wenchuan landslide debris over centennial timescales. However, future sediment export rates are likely to vary because of changes on hillslopes (for example, revegetation) and in hydrology, sediment characteristics and transport processes. Our findings demonstrate a decadal bedload-dominated sediment pulse driven by earthquake-triggered landslides, suggesting that increased vulnerability to cascading hazards such as aggradation and flooding could persist for decades in populated downstream regions after a large earthquake.

DOI: 10.1038/s41586-025-09354-8

Source: https://www.nature.com/articles/s41586-025-09354-8