基于时序InSAR技术的常州市地面沉降监测与分析

Land Subsidence Monitoring and Analysis in Changzhou Based on Time Series Interferometry Methods

城市地面沉降不仅会对居民生命安全造成影响,而且也会给当地的社会经济造成损失。常州市位于长江三角洲地面沉降区,也是我国经济最发达的地区之一。因此地面沉降监测是常州市掌握地面沉降的动态,为防灾减灾提供决策依据的重要举措。本文采用SBAS InSAR方法对2012-2013年23景TerraSAR-X高分辨率雷达影像数据进行了地表形变的反演,获取了该时间段常州地区年均沉降速率和时序地表累积形变图。结果表明,在整个观测期间,常州市呈现出"全区基本保持稳定,武进区局部沉降严重"的特点。为此,我们利用PS-InSAR技术对武进区的地面沉降进行了重点监测,发现该区多条重要交通线路存在不同程度的地面沉降。最后我们结合历史监测结果和水文地质背景,揭示了常州地区近50年地面沉降的时空变化特征和规律。综合分析表明,地下水全面禁采后研究区地面沉降的确得到了有效控制,沉降速率减缓,甚至出现了回弹。而武进地区的地面沉降虽然也在减缓,但仍然存在明显的地面沉降,一些重要交通线路的周边沉降已超过安全阈值,有必要在常规监测的同时,对这些沉降严重的区域进行重点监测,并建立预警预报机制,在城市基础设施选址和规划时提供决策依据。

Urban land subsidence not only threatens the life safety of local residents, but also causes great losses to the local social economy. Changzhou is located in the land subsidence zone of the Yangtze river delta, which is also one of the most economically developed areas in China. It is of great significance to carry out land subsidence monitoring in Changzhou city to map and detect ground subsidence, so as to provide help to decision making for disaster prevention and reduction. This manuscript used twenty-three TerraSAR-X high-resolution radar images and adopted SBAS InSAR method to obtain the average subsidence rate and cumulative time series of surface deformation during the observation period. The temporal and spatial evolution characteristics of surface deformation in Changzhou from 2012 to 2013 had been analyzed. The results show that during the entire observation period, the overall land subsidence characteristics of Changzhou city can be summarized to as “the whole area is basically stable and the local settlement in Wujin district is serious”. Besides that, the PSInSAR method was used to reveal the specific spatial-temporal characteristic of land subsidence around the important transportation lines in Wujin district, Inhomogeneous land subsidence were detected around these transport lines, which should be raised great attention to. Finally, we combined the historical monitoring results and hydrogeological background to reveal the temporal and spatial characteristics of land subsidence in Changzhou during the last fifty years. Comprehensive analysis showed that the ground subsidence in the study area after the groundwater was completely forbidden had been effectively controlled, the subsidence rate had been slowed down, and surface rebound had occurred. Although the land subsidence in the Wujin area was also slowing down, obvious subsidence was still witnessed in that area. The subsidence around some important traffic lines had exceeded the safety threshold. Enhanced monitoring of these areas was necessary as well as the routine monitoring in the whole study area. Besides that, early warning systems and forecasting mechanism for hazards, site selection and planning for new urban constructions should be conducted in order to provide valuable information for decision making.