Using D-insar To Monitor The Motion Of Frozen Ground In Qinghai-tibet Plateau

Frozen ground is widely distributed in China. The frozen ground area, which is sensitive to the air temperature, has the properties of frost heave and thawing settlement and thus relates closely with the people's production and living in these area. Conventional methods, e.g. precise leveling and GPS, are ineffective in these areas as they are covered by complex terrain, some even unreachable by mankind. Therefore, it's difficult to monitor the surface deformation and to obtain the entire deforming trend of the whole frozen ground area.As an important branch of InSAR technology, D-InSAR has the features of all-weather, wide spatial coverage and high precision. Thus it has aroused increasingly more attention and applications, especially in the monitoring of surface deformation caused by natural disasters, where very subtle surface can be deteced by DInSAR. D-INSAR technology provides an opportunity to improve the traditional monitoring methods.In this paper, the D-InSAR technology is used to monitor the surface deformation of permafrost area in Lhasa and its nearby region. A multi-aspective deforming rule of permafrost is analyzed based on spot, line and surface. The research obtains the typical deformation law of six typical ground coverages and forecast the deformation trend of the permafrost for the future 50 years. The main work are as follows:(1) The deformation property of frozen soil is analyzed. Then the configuration of parameters in differential interferometry data processing parameters are studied, which mainly contains coherence threhold, multi-look number and phase unwrapping parameters.(2) ALOS PALSAR and Envisat ASAR data are applied for analyzing the regional surface deformation of Lhasa area in Qinghai-Tibet Plateau. Based on the analysis, the conclutions, e.g. the deformation has great relationship with temperature, terrain, river system and active layer, are drawn.(3) Time series analysis of performast deformation are made based on the Envisat ASAR data. Six types of special features in Lhasa area, i. e., alpine grassland, the Peak, The sunny side of slopes, Dorsal-yang side of slopes, Qinghai-Tibet Railway, Qinghai-Tibet Highway, are chosen for permafrost area deformation modeling. It was found that the linear deformation rate varies from 0.04mm to 1.3 mm per year, and the amplitude of periodic deformation changes from 16.07 to 44.10 mm.(4) According to results of the deformation models and the properties of the frozen ground area, it is estimated that most of the qinghai-tibet plateau area will experience subsidence in the level of 4～5 centimeters in the next 50 years. The regional deformation of the land without artificial activities will be relatively small. Finally, suggestions on the treatment of performost deformation are given on the base of the currently method.