ISSN 1003-8035 CN 11-2852/P

    基于树轮地貌学的桑谷沟流域冰川型泥石流灾害史重建

    Reconstruction of glacial debris flow history in the Sanggu watershed based on dendrogeomorphology

    • 摘要: 扎墨公路的桑谷沟流域近年来冰川型泥石流频发,严重威胁对外边境廊道安全。了解并掌握该流域泥石流历史可以为未来气候变化背景下泥石流预测预报提供宝贵数据支撑。文章基于树木年轮生长,分析树木在泥石流干扰下产生的伤疤以及年轮生长释放/抑制等现象,基于修订后的年轮生长释放/抑制阈值,计算加权指数Wit值,重建桑谷沟流域1925—2021年的泥石流暴发时间及淹没范围,结合像元二分模型解译遥感影像获得的泥石流实际暴发时间和范围,验证新的年轮生长释放/抑制阈值及方法的合理性。研究结果表明:(1)在桑谷沟流域冰川型泥石流重建的过程中,弱、强年轮生长释放/抑制阈值分别修订为25%和50%,对年轮生长释放/抑制阈值进行修订将显著提高泥石流事件的识别精度;(2)在老龄树广布区域,排除生长释放这一因子计算Wit值,将降低冰川型泥石流定年的准确性;(3)对于缺乏泥石流历史资料的地区,结合遥感影像解译树轮地貌学的方法能够有效提高泥石流定年的准确性,尤其在遥感影像与年轮数据结合的背景下,能够更全面地重建泥石流的历史和范围。

       

      Abstract: In recent years, frequent glacial debris flows in the Sanggu watershed along the Zamo Highway have posed a serious threat to the safety of external border corridors. Understanding the historical occurance of debris flows in this watershed is crucial for improving prediction and early warning of debris flow under future climate change conditions. This paper analyzes tree-ring scars and growth release/suppression responses caused by debris flow disturbances based on tree ring growth. Based on revised thresholds for tree-ring growth release and suppression, Wit values were calculated to reconstruct the timing and inundation extent of debris flows in the Sanggu watershed from 1925 to 2021. The reconstructed events were validated using debris flow timing and extent extracted from remote sensing imagery interpreted via the pixel binary model. The results show that: (1) In the process of reconstructing glacial debris flow in the Sanggu watershed, the weak and strong thresholds for tree-ring growth release/suppression were revised to 25% and 50%, respectively. This revision significantly improves the accuracy of debris flow event identification. (2)In area dominated by old-growth trees, excluding growth releases as a factor when calculating Wit values reduces the dating accuracy of glacier-type debris flows. (3) In regions lacking historical debris flow data records, combining remote sensing image interpretation with dendrogeomorphology effectively enhance dating accurancy. The integration of remote sensing data and tree-ring records enables a more comprehensive reconstruction of debris flow history and extent.

       

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