易贡藏布流域崩滑灾害空间分布特征及其易发性评价研究

    SPATIAL DISTRIBUTION CHARACTERISTICS AND SUSCEPTIBILITY ASSESSMENT OF COLLAPSES AND LANDSLIDES IN THE YIGONG ZANGPO RIVER BASIN

    • 摘要: 易贡藏布流域内水能资源丰富,是雅鲁藏布江下游水电开发“阶梯式推进”的重要先行区。然而,区内山高坡陡、岩体破碎,大规模崩滑灾害频发,为区内水电工程开发带来极大的威胁。为揭示易贡藏布流域崩滑灾害空间分布规律及其主控因素,进而评估区内崩滑灾害易发性,本文采用遥感影像解译结合现场调查,查明区内崩滑灾害空间分布规律并对其主控因素进行分析。同时,分别采用频率比模型(FR)、归一化频率比模型(NFR)以及归一化频率比-逻辑回归耦合模型(NFR-LR)对区内崩滑易发性进行了评估预测。研究结果表明:(1)易贡藏布流域内共发育崩滑灾害705处,崩滑灾害在易贡措-夏曲水电站、忠玉-金桥-龙眼水电站等区段形成高密度核。(2)流域内崩滑灾害发生的有利条件包括:距水系小于1 km,高程小于4500 m,坡度大于30°,SE、S、SW坡向,地形起伏度大于450 m,距断层0.1~4 km,NDVI大于0.45,道路密度大于0.1 km·km-2,较软弱岩组等。(3)FR、NFR和NFR-LR等3种模型的预测精度指标AUC值均大于0.85,中等以上易发区中崩滑占比分别达到90.92%、98.30%、89.64%。(4)NFR-LR耦合模型预测AUC值最大(0.870),其优化了易发性分级区划精度,在精准识别高易发性区的同时,能够有效排除低风险区,有利于简化防灾决策。

       

      Abstract: The Yigong Zangpo Basin is characterized by steep terrain and fragmented rock masses, resulting in frequent large-scale collapses and landslides that pose serious risks to hydropower development in the area. This study utilized remote sensing image interpretation and field surveys to identify the spatial distribution patterns of landslides and analyze their controlling factors. Landslide susceptibility was assessed and predicted using the Frequency Ratio(FR)model, the Normalized Frequency Ratio(NFR)model, and a coupled NFR-Logistic Regression(NFR-LR)model. The results indicate that: (1)A total of 705 collapses and landslides were identified, forming high-density clusters in areas such as the Yigong Lake-Xiaqu hydropower station section and the Zhongyu-Jinqiao-Longyan hydropower station section. (2)Favorable conditions for collapses and landslides in the basin include: proximity to rivers within 1 km, elevations below 4500 m, slope gradients steeper than 30°, southeast-, south-, and southwest-facing aspects, topographic relief greater than 450 m, distances to faults between 0.1 km and 4 km, NDVI values above 0.45, road density exceeding 0.1 km·km-2, and the presence of weaker rock groups. (3)The prediction accuracy(AUC)of all three models(FR, NFR, and NFR-LR)exceeded 0.85. The moderate-to-high susceptibility zones delineated by these models contained 90.92%, 98.30%, and 89.64% of the documented collapses and landslides, respectively. (4)The coupled NFR-LR model achieved the highest prediction accuracy(AUC=0.870). It improved the precision of susceptibility classification, enabling accurate identification of high-susceptibility areas while effectively excluding low-risk zones, thus supporting more efficient disaster prevention decision-making.

       

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