形变监测是海塘安全运行的重要组成部分。本文利用杭州地区2006年—2010年获取的31景Envisat-ASAR影像,根据MTInSAR(Multi-Temporal InSAR)方法,综合提取PS(Persistent Scatterer)和DS(Distributed Scatterer)点,得到密集的钱塘江海塘形变的InSAR测量结果。与28个点的水准数据对比表明,两者的平均误差为0.436 mm,最大误差为5.016 mm,验证了InSAR技术毫米级的测量精度和准确性。通过这两种数据的时间序列分析发现,海塘的沉降在空间上具有连续性,其空间分布呈现为单峰下沉曲线;在时间上,则具有明显的线性变化规律,并伴随有短时间范围的小幅度波动。
Deformation monitoring is essential to the safe operation of seawalls. This paper reports the Interferometric Synthetic Aperture Radar (InSAR) measurement results derived from 31 Envisat ASAR images acquired over Hang zhou from 2006 to 2010,with special focus on the seawall in the Qiantang Estuary. Multi-temporal InSAR (MTInSAR) was used to extract deformation information from both Persistent Scatterers (PSs) and Distributed Scatterers (DSs), which provide dense measurement of the deformation of the seawall. Compared with the leveling measurement at 28 points, the mean error derived by InSAR is 0.436 mm, with the largest error of 5.016 mm, which confirms the millimeter-level precision and accuracy of the InSAR technique. A time series analysis was conducted based on these two datasets, and results showed that the subsidence of seawalls was spatially continuous and had a local negative unimodal pattern with distance. A linear tendency with minor local fluctuation was also observed in the time domain during a period of nearly seven years.