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    区域多尺度地面沉降时空变化特征分析

    Analysis of the spatiotemporal variation characteristics of regional multi-scale land subsidence

    • 摘要: 快速、不均匀的地面沉降对人类的生命和生产活动构成了严重威胁,了解地面沉降的时空演化规律对于精确的地质灾害防控至关重要。该文基于永久散射体合成孔径雷达干涉测量(persistent scatterer interferometric synthetic aperture Radar,PS-InSAR)技术获取山东省德州市的逐月地表形变信息,计算多尺度形变增量(subsidence vertical increment,SVI),并结合时间序列聚类分析、时空立方体、时空热点分析和时空异常值分析方法来探究德州市2017年7月—2021年12月多尺度SVI的时空分布特征。结果表明: 通过时空序列聚类,月尺度趋势聚类不明显,季节尺度和半年尺度聚类特征更显著,且半年尺度的沉降波动较大; 通过时空立方体模型呈现,月尺度的SVI连续性较差,沉降变化特征不明显,季节尺度和半年尺度沉降发生月份较为接近,呈现出每年3—8月沉降,9月—次年2月回弹的显著性规律; 对德州市54个月的半年尺度SVI时空热点分析可知,加强的沉降和连续的沉降主要发生在武城县、德城区的西北部,东南部的临邑县、禹城县和齐河县主要为振荡的沉降和振荡的回弹; 对多尺度SVI进行局部异常值分析可知,月尺度的沉降特征无明显规律,季度尺度和半年尺度的沉降情况相近,东部及东南部的临邑县、齐河县季节性沉降和与作物生长相关的半年尺度沉降均呈逐渐减弱,甚至回弹趋势,但半年尺度高-高聚类范围更广,回弹现象更显著。

       

      Abstract: Rapid and uneven land subsidence severely threatens human life and production activities. Understanding the spatiotemporal evolutionary patterns of land subsidence is crucial for the precise prevention and control of geological disasters. Employing the persistent scatterer interferometric synthetic aperture Radar (PS-InSAR) technology, this study obtained the information of monthly surface deformation in Dezhou City to calculate the multi-scale subsidence vulnerability indices (SVI). Combining time series cluster analysis, space-time cube, spatiotemporal hot spot analysis, and spatiotemporal outlier analysis, this study explored the spatiotemporal distribution characteristics of multi-scale SVI in Dezhou City from July 2017 to December 2021. The time series cluster analysis reveals inconspicuous trend clustering on a monthly scale, and significant clustering characteristics on quarterly and semi-annual scales, with large subsidence fluctuations on a semi-annual scale. The space-time cube model presents poor continuity of SVI and subtle subsidence variations on a monthly scale. In contrast, the subsidence on quarterly and semi-annual scales exhibited relatively close occurrence time, showing a significant pattern of subsidence from March to August and rebound from September to February of the ensuing year. The spatiotemporal hot spot analysis of SVI in Dezhou City for 54 months shows that enhanced and continuous subsidences occurred primarily in the northwest of Wucheng County and Decheng District. Oscillatory subsidence and rebound occurred principally in Linyi, Yucheng, and Qihe counties in the southeast. The local outlier analysis of multi-scale SVI shows nonsignificant subsidence characteristics on a monthly scale but similar subsidence conditions on quarterly and semi-annual scales. Seasonal subsidence and semi-annual subsidence related to crop growth in Linyi and Qihe counties gradually weakened or even rebounded. Notably, the high-high clustering range on a semi-annual scale was broader, accompanied by a more significant rebound.

       

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