基于小基线集时序干涉雷达分析武汉中心城区地表沉降时空特征

利用2015—2016年期间获取的15景Sentinel-1A TOPS SAR影像,采用小基线集时序干涉雷达(interferometric syn-thetic aperture radar,InSAR)分析方法,研究了武汉中心城区的地表沉降特征,分析并建立了该地区地表沉降与城市建设、降雨量和长江水位变化等因素的关系.采用32个水准点数据验证了基于Sentinel-1A反演的地表沉降结果,精度为5.82 mm/a.研究区域内不均沉降明显,其地表沉降速率范围为-81.5～18.2 mm/a,且探测到的最大沉降速率位于后湖地区;地表沉降时间序列呈伴随有明显季节变化的非线性沉降.地表沉降与影响因子的对比分析表明,沉降漏斗与工程建设施工区位置分布具有较高的空间相关性;地表沉降中的季节性变化与水位变化和降雨量有关;研究区域地表沉降主要由人为活动、土层压缩性以及地下水过度开采等造成.研究结果给出了武汉中心城区地表沉降时空特征和地表沉降与其影响因子之间的相互关系.

Spatial-temporal Characteristics Analysis of Surface Subsidence in Central Urban Areas of Wuhan Based on Small Baseline Subset Interferometric SAR

In this paper, surface subsidence characteristics in central urban areas of Wuhan was investigated using 15 Sentinel-1A Terrain Observation with Progressive Scans (TOPS) SAR images acquired from 2015 to 2016 with the Small Baseline Subset Interferometric SAR (SBAS InSAR) analysis method. The correlations between surface subsidence and urban construction, precipitation, and water level changes in Yangtze River in the study area were analyzed and established. The inversion surface subsidence results based on Sentinel-1A were validated by 32 leveling points at an accuracy of 5.82 mm/year. Prominent uneven subsidence patterns were identified in the study area. Specifically, surface subsidence rates ranged from ?81.5 mm/year to 18.2 mm/year, and maximum subsidence rate was detected in Houhu areas. Surface subsidence time series presented nonlinear subsidence with pronounced seasonal variations. Comparative analysis of surface subsidence and influencing factors indicated a relatively high spatial correlation between locations of subsidence bowl and those of engineering construction. Seasonal variations in subsidence were correlated with water level changes and precipitation. Surface subsidence in the study area was mainly attributed to anthropogenic activities, compressibility of soil layer, and groundwater overexploitation. The spatial-temporal characteristics of surface subsidence and the relationship between surface subsidence and influencing factors in central urban areas of Wuhan were given in the results of this study.