The Andes region exhibits high susceptibility to landslides, leading to significant infrastructure, road, and agricultural damage. This study focuses on Ciudad Victoria, a housing program located in a geologically unstable area of Loja, Ecuador. Loja has experienced frequent landslides in recent decades, with Ciudad Victoria initially affected in 2011 and 2015, intensifying during the rainy season in early 2021. However, a comprehensive understanding of this case is currently lacking. Here, we evaluate terrain instability and structural damages through a comprehensive multi-technical approach. In this study, we integrate advanced techniques such as Differential Interferometric Synthetic Aperture Radar (DInSAR), Uncrewed Aerial Vehicles (UAV)-supported field surveys, geomorphological assessments, Electrical Resistivity Tomography (ERT), and a semi-quantitative evaluation of house damages using a Geographic Information System (GIS). The combined analysis of DInSAR, field surveys, and geomorphological observations reveals that soil instability in Ciudad Victoria is primarily influenced by slow-moving translation-type landslides occurring in the SW-NE and S-N directions. These landslides exhibit an average active displacement of 1-4 cm/yr, which increases during the rainy months, reaching velocities of up to 13 cm per month. ERT, supported by the aforementioned observations, indicates a displaced soil volume of approximately 5 Hm3, 3 , with dimensions of roughly 700 m (length), 400 m (width), and 20 m (thickness). A semi- quantitative evaluation reveals that four houses have irreversible structural damages, while 172 houses exhibit severe damage and 553 houses display moderate damages such as cracks and fractures, which also impact water and sewage pipelines. Additionally, we demonstrate how these building damages can be utilized to determine terrain movement, serving as (1) ground-truth information for validating DInSAR data, and (2) facilitating detailed movement characterization. This study exemplifies the effectiveness of coordination among a multidisciplinary team that utilizes diverse techniques and perspectives, ultimately leading to a more precise diagnosis of unstable areas.
Global sea level rise (SLR) has emerged as a pressing concern because of its impacts, especially increased vulnerability of coastal urban areas flooding. This study addresses the pressing concern of SLR and flood vulnerability in the East Coast of North Sumatra (ECNS) and Medan City. We employ a data-driven approach integrating multicriteria analysis, analytical hierarchy process (AHP)-based weighting, and spatial modeling within a geographic information system framework. The analysis considers crucial factors such as slope, land use, soil type, SLR, and land deformation. The study expands the existing framework by incorporating SLR and land subsidence, acknowledging their significant roles in exacerbating flood vulnerability. Future flood-intensity scenarios are simulated based on SLR projections. Data for spatial analysis primarily originated from multisensor satellite imagery, secondary sources from published literature, and field surveys. We validated the consistency of the variable weightings assigned for vulnerability analysis using a consistency ratio threshold (<0.1). Finally, the established flood vulnerability model was validated by comparing its predictions with recorded flood events in the ECNS and Medan City. The ECNS and Medan City areas were classified as very high and highly vulnerable to flooding, respectively.
冰川触地线是内陆冰盖和漂浮冰架的分界线，其位置的准确界定对南极冰川物质平衡计算、冰川动力学建模、冰川变化和海平面变化研究具有重要意义。本文针对Sentinel-1A/B雷达影像数据在南极触地线大规模提取中的应用，基于2020年Sentinel-1A/B雷达影像数据，采用DDInSAR方法对南极触地线进行了大范围的提取，提取触地线约23 472 km,结合MEaSURE＿GL、MOA＿GL2009、MEaSUREs冰流速等数据对触地线提取结果进行综合分析。结果表明：利用DDInSAR方法和Sentinel-1A/B雷达影像数据可以实现对南极触地线长期、高效且较全面的提取，南极不同地区的触地线具有不同的变化特征，存在稳定、回退、前进、消失和冰升等多种变化现象。南极半岛和西南极可以完全应用6 d的Sentinel-1A/B雷达影像数据提取触地线，东南极大部分区域只能应用12 d的Sentinel-1A/B雷达影像数据提取触地线。潮汐运动的强弱影响触地线的提取质量，在西南极的强潮汐区域触地线提取质量较高，在东南极冰盖周围的弱潮汐区域触地线提取质量较差或者结果空缺。南极触地线的提取受冰流速影响较...
季节性冻土的冻胀和融沉对铁路既有线路基、边坡以及周围设施的冻害多呈区域性和周期性,传统监测技术手段难以达到足够的时空分辨率,引入毫米级时序DInSAR技术十分必要。选取季节性冻土较发育的黑龙江某既有线作为研究对象,根据其沿线区域地形和地质特点,采用针对性的选点方法以及基于多主影像干涉的时序DInSAR误差改正及解算模型,使用时间基线长达两年(2017年9月至2019年7月)的高时间密度48景中等分辨率Sentinel-1A SAR影像,获取自联调联试至目前运营期间沿线区域沉降的时空分布结果,通过与该区域冻融时间点的联合分析,获得冻土冻胀和融沉对铁路沿线区域沉降影响的时空分布规律,可为该区域季节性冻土的时空演变规律提供参考数据。
由于印度洋季风的影响，位于藏东南的岗日嘎布是青藏高原最湿润的地区，海洋性冰川在该地区集中发育。该地区的冰川物质损失对海平面上升、调节河川径流及冰湖溃决灾害等有重要影响。本文基于1980年航测地形图、2000年2月11–22日SRTM数字高程模型（DEM）和2014年的X波段TerraSAR/TanDEM雷达影像得到岗日嘎布地区冰川高程变化。大致空间范围在29°N–30°N、96°E–98°E内，包括帕隆藏布以南、贡日嘎布曲以北区域，覆盖面积达3600平方公里。数据集内包含两类文件：1）基于TerraSAR/TanDEM雷达影像获取的2014年数字高程模型数据；2）基于地形图、SRTM和TerraSAR/TanDEM雷达影像获取的1980–2014年冰川高程变化栅格数据。为克服岗日嘎布地区多云雨对光学遥感影像的影响，对大地测量法中数字高程模型及冰川高程变化的提取采用合成孔径雷达差分干涉测量（DInSAR）。与ICESat-GLAS数据相比较，2014年数字高程模型的垂直精度达到2.65 m。利用DInSAR获取的冰川高程变化转化为物质平衡，与野外测量获取的冰川物质平衡有较好的一致性。本数...
Investigations into the susceptibility of permafrost landscapes response to thermokarst can be performed using various approaches, depending on the scale of investigation. In many cases, point-based field measurements are extrapolated to larger scales and vice versa. The integration of scales often requires some form of ground control in addition to remote sensing surveys, which are at times exclusively conducted. As upscaling from discrete field measurements can provide spatial coverage and landscape-scale significance, downscaling from remote sensing can offer insight into processes and serve as calibration or verification. Here we present a multiple-scale evaluation of an area initially interpreted as a relict active layer detachment slide (before 1950) on Melville Island in the High Arctic, where differential interferometric synthetic aperture radar (DInSAR) showed subsidence between 2013 and 2015. Ground-based, cryostratigraphy measurements were combined with ground-penetrating radar (GPR) to investigate permafrost ice-content. The results indicate greater subsidence within the relict active layer detachment as detected by DInSAR. GPR surveys and permafrost coring indicated the presence of an ice-rich or massive ice layer near the base of the active layer in this area. In addition, cryostratigraphic evidences of thaw unconformity and of massive ice depth helped validate the interpretations of the geomorphology in the active layer detachment. This combination of methods indicated a localized and inherited landform-subsidence association, which brought further insight into the interpretation of DInSAR subsidence data. The framework presented in this study demonstrates the importance of site-specific investigations of thermokarst signal in order to understand the processes behind the remote sensing results. (C) 2020 Elsevier B.V. All rights reserved.
多年冻土是青藏高原主要的,也是关键的土壤类型。其发生、发展对青藏高原生态、水文等都有重要的影响。自出现合成孔径雷达干涉技术(Interferometric Synthetic Aperture Radar,In SAR)以来,对多年冻土区土壤冻融的研究就出现了一种新的手段,利用该方法可以有效探测近地表土壤的冻融状态。本文首先介绍了多年来各国的星载合成孔径雷达(SAR),然后阐述了该方法的理论基础,最后对差分干涉合成孔径雷达技术(D-In SAR)、小基线子集方法(Small Baseline Subset Approach,SBAS-DIn SAR)和永久散射体技术(Permanent Scatterers,PS)都做出了描述。综上所述,利用适合的SAR数据和有效的In SAR方法研究青藏高原冻土区的冻融状况,可以为今后的科学研究提供范围广、类型多样、精度高的基础数据。