武汉市地面沉降时空分异特征及地理探测机制

城市地区地面沉降造成地面高程损失，威胁各类设施的安全运行，影响地表径流和水文循环，监测地面沉降现状并揭示其形成机制，对于城市可持续发展具有重要意义。以2007—2011年的ALOS-PALSAR影像和2015—2019年的Radarsat-2影像为数据源，基于小基线集技术（small baseline subset interferometric synthetic aperture radar, SBAS-InSAR）获取武汉市两个监测阶段的地面沉降速率、沉降时间序列，并利用地理探测器揭示规划单元尺度地面沉降的主导驱动因子及驱动因子之间的交互作用机制。结果表明:(1)2007—2011?年和2015—2019年地面沉降平均速率分别为-3.53 mm/a和-1.48 mm/a。地面沉降较为显著的区域:2007—2011年，是汉口、沙湖沿岸及以北、南湖以西和白沙洲地区；2015—2019年，是汉口、沙湖北和白沙洲地区。(2)?局部性、阶段性、与自然条件及人类活动相关是两个时期武汉市地面沉降演变的3个特点。(3)水文地质条件作为必要条件，通过与地面荷载、地下空间开发、工程施工因素交互作用形成武汉市地面沉降时空格局，2007?—2011年的工程施工因素、2015—2019年的地面荷载因素与水文地质条件交互作用明显较强。

Spatial-Temproal Variation Characteristics and Geographic Detection Mechanism of Land Subsidence in Wuhan City from 2007 to 2019

  Objectives  Land subsidence in urban areas brings loss of ground elevation, damages urban infrastructure and buildings, and affects surface runoff and hydrological cycle. Monitoring the status of land subsidence and revealing its formation mechanism is of great significance for sustainable urban development.  Methods  Using ALOS-PALSAR images from 2007 to 2011 and Radarsat-2 images from 2015 to 2019 as data sources, based on SBAS-InSAR technology to obtain the land subsidence rate and time series, and us?ing geographic detectors to reveal the dominant driving factors and the interaction mechanism between the driving factors of land subsidence at the scale of planning unit.  Results  The results show that: (1)The average land subsidence rates from 2007 to 2011 and from 2015 to 2019 were -3.53 mm/a and -1.48 mm/a, respectively. The hot spots for land subsidence from 2007 to 2011 are Hankou, the coast and north of Shahu Lake, the west of Nanhu Lake, and the Baishazhou area. From 2015 to 2019, it is Hankou, the north of Shahu Lake and the Baishazhou area.(2)The temporal and spatial evolution of land subsidence in Wuhan is localized, staged, and related to natural conditions and human activities. Rapid subsidence only occur in certain region, shows the different trends at various stages, and is closely related to the regional natural conditions and human activities.(3)Hydrogeological conditions are necessary conditions to form the spatial-temporal pattern of land subsidence in Wuhan through interaction with various factors such as ground load, underground space development, and engineering construction. The interactive effects between engineering construction and hydrogeological conditions from 2007 to 2011 are found to be significant, so do ground load and hydrogeological conditions from 2015 to 2019.  Conclusion  The geographic detector can quantitatively identify the driving factors of land subsidence and the interactions between them. The interactive effects between hydrogeological and conditions engineering construction, ground load to a large extent affected spatial variation of land subsidence from 2007 to 2011 and from 2015 to 2019 respectively. In the future, continuous monitoring of land subsidence and multi-scale research on the formation mechanism of land subsidence should be carried out to further enrich the theory and method system of land subsid?ence research.