Application Of D-InSAR For Land Subsidence Monitoring In Panjin

Land subsidence is the ground deforming perpendicular to the surface due to the natural andartificial factors. China has different degrees of regional land subsidences which have become oneof the major geological disasters restricting regional environmental and social-economicsustainable development. Differential interferometry on Synthetic Aperture Radar (D-InSAR)technique, as a new ground monitoring technology，can be used for the monitorings of earthquake,volcanic activity, glacial drift, land subsidence，landslide and other small surface deformation. Itsmeasuring accuracy can reach centimeter level or even millimeters. Compared with conventionalmonitoring techniques, D-InSAR technique is of the dominances of all-day, all-weather, largemonitoring area, fast, accurate and low cost.Applying the D-InSAR technique and the6pictures of ALOS PALSAR data and combiningwith STRM DEM data, this thesis deals with the land subsidence in Panjin through imageregistration,filtering of interference images,eliminating flat effect, unwrapping phase，minus reliefphase and geographic coding.There are six land subsidence areas called Dongguoweichang(A), Huanxiling(B),Xibaqianxiang(C) and Panjin city(D) in Panjin area. Of them,the Dongguoweichang(A)subsidence area is4.22km2and the long axis of the oval subsidence area strikes in NE-SWdirection.The cumulative subsidence amplitude of the area between2007and2011is-746mm andthe average subsidence velocity is228mm/a.The Huanxiling(B) subsidence area is circular inplane shape with an area of0.94km2. The cumulative subsidence amplitude between2007and2011is-263mm and the average subsidence velocity is86mm/a. The Xibaqianxiang(C)subsidence area is4.38km2and the long axis of the oval subsidence area strikes in NE-SWdirection.The cumulative subsidence amplitude between2007and2011is-414mm and theaverage subsidence velocity is124mm/a. The Panjin city(D) subsidence area is small and performsin dispersal points.The cumulative subsidence amplitude between2007and2011is-70mm andthe average subsidence velocity is23mm/a.Through the time series analysis of land subsidence,we get that the subsidence area of theDongguoweichang(A) is becoming larger and its subsidence velocity is becoming smaller. Thesubsidence area of Huanxiling(B) is becoming smaller little by little and its subsidence velocity isbecoming smaller in wave up and down.The Xibaqianxiang(C) subsidence area is becoming largerbut its subsidence velocity is becoming smaller in wave up and down. The subsidence velocity ofPanjin city(D) is changing in wave up and down.The tree branches cut and minimum cost flow unwrapping methods are used and thecalculated results are compared.The tree branches cut method unwraps directly interference phasesand determines the amplification-narrow factor modeling relief phases by least square method inorder to improve the simulated relief phases.The minimum cost flow method does’t need tounwrap interference phases, and even though the interference phases can not be successfullyunwrapped, the reasonable results can also be calculated. The two methods give consistent resultsin the calculation. The largest subsidence values of the Dongguoweichang(A), Huanxiling(B),Xibaqianxiang(C) and Panjin city(D) are separately-176mm,-88mm,-99mm and-28mm got bytree branches cut method and-169mm,-78mm,-105mm and-16mm got by minimum cost flowmethod.The calculated results by minimum cost flow method are generally smaller than that bytree branches cut method. The tree branches cut method with a quicker calculation is appropriate for the unwrapping calculation of plain area but the minimum cost flow method considering globaloptimum is suitable for the unwrapping calculation of plain and mountain area.