20世纪60年代以来,北京市地面沉降不断发展,目前已经形成了东郊八里庄-大郊亭、东北郊-来广营、昌平沙河-八仙庄、大兴榆垡-礼贤和顺义平各庄5个沉降区。本文选取目前地面沉降较为严重的北京市朝阳区、顺义区和通州区作为研究区,利用2003-2010年的47景ASAR影像数据,采用SBAS-InSAR技术获取了研究区的地面沉降监测结果,并分别以SFP点年均沉降速率和各年沉降量作为权重,计算SFP点空间分布中心与方向特征椭圆,定量分析了研究区地面沉降时空特征。结果表明:2004-2010年,北京市地面沉降表现为严重的不均匀沉降,年沉降量最大值由104.04 mm增加到178.83 mm;标准差椭圆长轴与南北方向平行,反映出地面沉降空间发展方向性在南北方向较东西方向明显,椭圆面积由592.25 km2减小到503.84 km2,表明2004-2010年研究区内发生地面沉降的区域范围变化呈减小趋势,但从沉降量可以发现,北京地面沉降一直处于加重趋势。
Land subsidence in Beijing has developed since 1960s. Five major subsidence areas have formed: Dongjiao Ba Lizhuang-Da Jiaoting, Dong Beijiao-Lai Guangying, Changping Shahe-Ba Xianzhuang, Daxing Yu- fa-Lixian, and Shunyi-Ping Gezhuang. In this study, we investigated Chaoyang, Shunyi, and Tongzhou Districts, which have experienced relatively serious subsidence, and obtained land subsidence monitoring results using data from 47 ASAR images (2004-2010) and the technology of small baseline subset interferometric synthetic aperture radar (SBAS-InSAR). Weighted by the annual average subsidence rate of SFP points and the subsidence amount of each year, we calculated the spatial distribution center of SFP points and the eigenellipse to quantatively analyze the spatiotemporal characteristics of subsidence in the study area. In 2004-2010, Beijing experienced pronounced uneven subsidence, and annual maximum subsidence increased from 104.04 to 178.83 mm. The long axis of the eigenellipse was parallel to the north-south direction and it indicated that spatial development of land subsidence was more obvious in the north-south direction than that in the east-west direction. The eigenellipse area decreased from 592.25 to 503.84 krn: in 2004-2010. This result indicated that the subsidence area decreased, but the amount of subsidence still suggested increasing subsidence in Beijing.