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Summary of Proposal COA1326

TitleSeawall Stability Monitoring with TerraSAR-X Interferometry in Zhejiang Province,China
Investigator Xie, Chou - Institute of Remote Sensing and Digital Earth, Chinese Academy of Science, Laboratory of Radar Remote Sensing
Team Member
Doctor Wan, Zi - Zhejiang Institute of Hydraulics and Estuary, Department of Information and Automation Technology
Doctor Liang, Fang - Institute of Remote Sensing Applications, Chinese Academy of Science, Laborary of Microwave Remote Sensing
Doctor Xie, Chou - Institute of Remote Sensing Applications, Chinese Academy of Science, Laborary of Microwave Remote Sensing
SummarySeawalls are the first line to defense coastal region from typhoon surge, and are important barriers related to regional economic and social development of coastal region. Zhejiang coastal area is in one of China's strong tide region, and it is often stroked by high tides and natural disasters, mostly caused by typhoons and storm surges. Moreover the seawalls are mostly constructed on deep soft ground, thus easy to deform and not stable. Under the influence of strong tide and storm surge for years, seawalls always have serious subsidence, and cracks and leakage occurs frequently in these seawalls.Monitoring the deformation of seawalls is of vital importance for avoiding catastrophic loss of infrastructure and life. Radar interferometry has proven to be an extremely reliable means of measuring subtle deformations of both natural and man-made structures with accuracies that span the levels of deformation that require monitoring. The large array of currently operating and planned earth observing orbiting radars coupled with advanced processing schemes such as permanent scatterer techniques can play a major rolein this regard. Moreover, high resolution SAR data provided by TerraSAR-X data will incur new types of deformation monitoring data products and professional services. The Project Team proposed to carry out InSAR-based analysis of seawalls subsidence in Zhejiang, China. With Project Team’s previous project results and the ground survey data obtained from the Project Team’s partner, this Project will scientifically prove the TerraSAR-X’s applicability. Therefore, the proposed project has two main objectives: •Monitoring of seawall’s subsidence using multitemporal interferograms with high-resolution TerraSAR-X image stacks. •Integrating InSAR, GPS and leveling data to determine seawalls displacement map. There are potentially a number of methods for determining seawall’s subsidence, e.g. stacking many short-interval interferograms, small-baseline time series methods, or the permanent/persistent scatterer approach. What all these methods require are multiple acquisitions of SAR scenes over as long a time as possible to allow the small signal associated with seawall’s subsidence to be extracted in the presence of significant environmental perturbations. This Project Team has analyzed temporal and spatial performance of interferometric phase caused by different components, and developed an independent InSAR time series techniques for separating different components and extracting information of seawall’s subsidence. At the same time, the team has GAMMA in hand, and can use IPTA method to analyze seawall’s subsidence. The team will develop a specific 3D unwrapping methodology adapted to the subsidence properties of seawalls. In this proposal, 70 TerraSAR-x images are needed. In addition to 50 StripMap data, 20 SpotLight mode data shall be analysed. On the one hand it is intended to gain experience with the new data with its higher resolution. On the other hand the possibility of increasing the accuracy, the quality and the reliability shall be investigated for both DInSAR and IPTA analyses in comparison to StripMap data. This work is sponsored by National Natural Science Foundation of China. Dr. Xie leads a project of detecting seawall’s subsidence using permanent scatterers interferometry. At the same time, the team also leads a current the Ministry of Water Resources, China-sponsored study of seawall risk assessment in Zhejiang, and Dr. Wan from ZIHE will be responsible for the in-situ campaign including leveling and GPS measurements.

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