Land Surface Deformation Monitored By Time Series InSAR Technique And Its Relationship With Groundwater Level Changes In Beijing

Land subsidence is the main regional environmental geological hazard in North China Plain.With the sharp development of economy,the sharp growth of population,the rapid increase of groundwater exploitation and the continuous expansion of urban and traffic construction,the problem of land subsidence in Beijing area is becoming more and more serious.However,the original traditional measurement method has high labor cost,long monitoring period,and is difficult to monitor for a long time.Due to the development of the small baseline subset interferometric synthetic aperture radar(SBAS-InSAR)technique,the above limitations are greatly exceeded.Only a few images are needed to obtain the deformation information of the study area.Using the SBAS-InSAR method,this paper selects 52 scene ENVISAT-ASAR data with time span from 18 June,2003 to 16 June,2010,and obtains the topographic transmission rate and cumulative subsidence time series of Beijing.Combined with the data of 24 continuous water level monitoring wells in the study area,the seasonal variation components of surface deformation and groundwater level are separated by using the method of multi-channel singular spectrum analysis,and the relationship of seasonal variation components is explored,and then the storage coefficient of elastic skeleton is calculated.The main achievements of this paper are as follows:(1)According to the results of deformation,the main deformation of cumulative deformation in Beijing from 2003 to 2010 is subsidence,the maximum subsidence rate is 58.4 mm/y,the maximum subsidence is 522 mm..The areas with lager subsidence mainly appear in the east of plain area,followed by the north,and the main urban area in the central and western regions is relatively stable.The subsidence is developed in the form of multi-center subsidence funnel,but because of the large range of subsidence funnel,a more continuous subsidence area has been formed.(2)Using the method of multichannel singular spectrum analysis,the components of surface deformation and water level change are separated.The results show that both of them contain obvious periodic changes,and there are seasonal variation components with one year period.At the same time,the interference caused by atmospheric delay is eliminated by Monte Carlo singular spectrum analysis.(3)Through the analysis of the correlation of land surface deformation and seasonal signal of water level,it is shown that there is a certain correlation between them.Finally,based on the change of surface shape and water level,the storage coefficient of elastic skeleton is calculated with the lag time.It provides some support for subsidence control and further study of groundwater aquifer system in Beijing.