tailieunhanh - Study of Subsidence detection by DinSAR and evaluation of some factors to the outcome

The study proves using DInSAR with Three-pass method would provide more reliable result as compared to the Two-pass method even with a limited amount of images. | Vietnam Journal of Earth Sciences 37 (2015) 344-354 Vietnam Academy of Science and Technology Vietnam Journal of Earth Sciences (VAST) Website: Study of Subsidence detection by DinSAR and evaluation of some factors to the outcome Tran Van Anh1, Tran Quoc Cuong*2, Nguyen Duc Anh2, Dang Vu Khac3 1 University of Mining and Geology, Hanoi, Vietnam 2 Institute of Geological Sciences, VAST, Hanoi, Vietnam 3 Hanoi National University of Education, Hanoi, Vietnam Accepted 25 December 2015 ABSTRACT The paper focuses on determining the subsidence by Differential Interferometric Synthetic Aperture Radar (DInSAR) using two methods (Two-pass and Three-pass) and assessing the effect of some error sources to the results. Errors effecting the result include atmospheric, phase due to signal-to-noise ratios, number of looks, pixel misregistration and baseline decorrelation; however, especially significant is (Digital Elevation Model) DEM error. We proved that application of DEM with low precision would create virtual subsidence. The experiment area is Hanoi city, data was Envisat ASAR image, C band with the wavelength of . By using SARscape software for processing, with Two-pass method a virtual subsidence was found at one site in northern part of Hanoi near the Red River (Song Hong). With the Three-pass method this subsidence site did not occurred. Besides, results of surface subsidence detection using DInSAR methods were compared with those measured directly from monitoring stations located close to water supplying wells. As a result, data acquired from Ha Dinh and Thanh Cong stations were closely distributedto those determined by DInSAR method. Unfortunately, the subsidence data acquired by direct measurement had been conducted continuously only from 2000 to 2003 instead to 2005; whereas the Envisat ASAR subsidence data are available only from 2003 to 2004. Therefore, combination of data of direct measurement at Ha Dinh and Thanh .