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Coal mining-induced ground subsidence is a severe hazard that can damage property, infrastructure, and the environment in the vicinity when the deformation is not negligible. The boundary of a mining-induced subsidence-affected zone refers to the area beyond which the ground subsidence is less concerned. Accurately measuring mining-induced ground deformation is essential for delineating the irregular boundary of the impacted area. This study employs multitemporal interferometric synthetic aperture radar (MT-InSAR) techniques, including differential InSAR (DInSAR), InSAR stacking, and interferometric point target analysis (IPTA), to analyze coal mine subsidence and delineate the boundaries of the mining-impacted zones. DInSAR accurately reconstructs, locates, and detects the trend in mining-induced subsidence and correlates well with documented mining operations. The InSAR stacking method maps the spatial variation of the ground's average line-of-sight (LOS) velocity over the mining area, delineating the boundary of the impacted zone. IPTA analysis combining multilook and single-pixel phases achieves millimeter-level surface measurement above tunnel alignments and measures unevenly distributed deformation fields. This study considers an average of 4 cm per year of surface deformation in the LOS direction as the subsidence threshold value for delineating the boundary of the mining-induced subsidence-affected (MISA) zone during the active coal mining stage. Interestingly, there are twin transportation tunnels near the mining area. The twin tunnels completed before the coal mining activities started were functioning well, but damage was observed after the mining began. Our study reveals the tunnels are located within the InSAR-derived MISA zone, although the tunnels approach the MISA boundary. As direct signs of subsidence, ground fissures have been identified near the tunnels via field investigations and UAV photogrammetry. Furthermore, the derived distribution of ground fissures validates and verifies InSAR measurements. The integrated approach of MT-InSAR, UVA photogrammetry, and field investigation developed in this study can be applied to delineate the irregular boundary of the MISA zone and study the accumulating effects of mining-induced subsidence on the performance of infrastructure in areas proximate to coal mining activities. [ABSTRACT FROM AUTHOR]

Urban flooding is becoming more frequent and severe due to the impact of climate change, underscoring the urgent need for effective flood risk management. This study investigates the dynamics of flood risk through two decades, from 2000 to 2020, in New Orleans, United States—a city historically marked by catastrophic flooding events. This research also explores the spatial patterns of socially vulnerable neighborhoods at the census tract level and patterns that have changed over the two decades. The Modified Normalized Difference Water Index (MNDWI) was used to indirectly evaluate flood risks over time utilizing Landsat 5 and Landsat 8 satellite imagery and geospatial analyses. Thematic mapping and geospatial analysis were used to generate maps revealing neighborhoods at the intersection of high flood risk and social vulnerability in New Orleans. Integrating flood maps derived from satellite observations with Social Vulnerability Index (SVI) calculations provides a comprehensive view of flood dynamics in the context of social vulnerability in an urban setting. The final composite products provide insight into zones where past resilience-building and risk-reduction efforts have reduced vulnerability in New Orleans and identify zones requiring intervention. The findings demonstrate how integrated data-driven analysis can inform urban infrastructure and policy development, thereby promoting discussions on urban resilience and the nuanced understanding of interactions between urban settings and flood risks, potentially aiding in implementing adaptive strategies to build resilience in New Orleans. [ABSTRACT FROM AUTHOR]

What are the dynamics of the participatory online discourse in an authoritarian context? More specifically, what patterns of Chinese state-society interactions can be drawn from the existing nexus of top-down control and bottom-up participation? To explore the questions, this study examines the Chinese nation-state personifications produced by 'fanquan girls', nationalistic fans of pop stars, during the 2019 Hong Kong protests. Three types of imageries and scenarios emerged, i.e., the nation as a charismatic idol in a discursive struggle, a protective brother on a battlefield, and a victimized mother in a trial. These visualizations construct a discursive kinship that justifies China's governance over Hong Kong and refutes the intervention from foreign 'hostile forces' through visualized national strength, state-society unity, and colonial sufferings. During the process, the state provided the ideological mindset and delimited the political boundaries, the fandom participants turned the state-promoted ideas and sentiments into youth-appealing memes, and both sides appropriated and circulated each other's creations in joint self-defense against outside reproval and opposition. Therefore, the paper argues that this communicative pattern consolidates the state's discursive co-optation of the society rather than demolishes the authoritarian rule. [ABSTRACT FROM AUTHOR]

Synthetic Aperture Radar (SAR) interferometry is a formidable technique to monitor surface deformation with a millimeter detection resolution. This study applies the Persistent Scatter-Interferometric Synthetic Aperture Radar (PSInSARTM) technique to measure ground subsidence related to a twin-tunnel excavation in downtown Los Angeles, USA. The PSInSARTM technique is suitable for urban settings because urban areas have strong reflectors. The twin tunnels in downtown Los Angeles were excavated beneath a densely urbanized area with variable overburden depths. In practice, tunneling-induced ground settlement is dominantly vertical. The vertical deformation rate in this study is derived by combining Line of Sight (LOS) deformation velocities obtained from SAR images from both ascending and descending satellite orbits. Local and uneven settlements up to approximately 12 mm/year along the tunnel alignment are observed within the allowable threshold. No severe damages to aboveground structures were reported. Furthermore, ground movements mapped one year before tunnel construction indicate that no concentrated ground settlements pre-existed. A Machine Learning (ML)-based permutation feature importance method is used for a parametric study to identify dominant factors associated with the twin-tunneling induced uneven ground subsidence. Six parameters are selected to conduct the parametric study, including overburden thickness, i.e., the thickness of artificial fill and alluvium soils above the tunnel springline, the distance between the two tunnel centerlines, the depth to the tunnel springline, building height, the distance to the tunnel, and groundwater level. Results of the parametric analysis indicate that overburden thickness, i.e., the thickness of artificial fill and alluvium soils above the tunnel springline, is the dominant contributing factor, followed by the distance between tunnel centerlines, depth to the tunnel springline, and building height. Two parameters, the distance to the tunnel, and the groundwater level, play lesser essential roles than others. In addition, the geological profile provides comprehension of unevenly distributed ground settlements, which are geologically sensitive and more concentrated in areas with thick artificial fill and alluvium soils, low tunnel depth, and high groundwater levels. [ABSTRACT FROM AUTHOR]