Yangbajain contains the largest geothermal energy power station in China.Geothermal explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal...Yangbajain contains the largest geothermal energy power station in China.Geothermal explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal fluids have been extracted since then,leading to considerable surface subsidence around the geothermal fields.In this paper,InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images.In the case of the TerraSAR-X data,most orbital fringes were removed using precise orbits during the interferometric processing.However,residual orbital ramps remain in some interferograms due to the uncertainties in the TerraSAR-X orbits.To remove the residual orbital ramps,we estimated a best-fit‘twisted plane’for each epoch interferogram using quadratic polynomial models based on a network approach.This method removes most of the long-wavelength signals,including orbit ramps and atmospheric effects.The vertically stratified component(Topography Correlated Atmospheric Delay,TCAD)was also removed using a network approach.If the influence of seasonal frozen ground(SFG)is not taken into consideration,our results show that the subsidence rate around power plant I(the south plant)is approximately 20 mm/yr with a peak of 30 mm/yr.The subsidence rate around power plant II(the north plant)is approximately 10 mm/yr,when accounting for the influence of SFG on the power plant and its surrounding ground surface.Our results show that ground motion is caused by seasonal frozen ground and is strongly related to the temperature change.展开更多
Erupting-flow types of geothermal wells in the Yangbajain geothermal field, China, are proposed based on internal energy of geothermal fluids and hydrogeologic-dynamic conditions of wellbore. An erupting-flow model, w...Erupting-flow types of geothermal wells in the Yangbajain geothermal field, China, are proposed based on internal energy of geothermal fluids and hydrogeologic-dynamic conditions of wellbore. An erupting-flow model, which is adaptable to the steaming and erupting of flow from wells in the field, has been verified by actual cases.展开更多
Digital elevation model （DEM） can be generated by interferometric synthetic aperture radar （InSAR）. In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, ...Digital elevation model （DEM） can be generated by interferometric synthetic aperture radar （InSAR）. In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite （ERS）-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1：50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared errors （RMSE）, which are used to evaluate error, are about 35, 60, 10, and 15 m in the studied area, mountainous area, basin area and near-fault area, respectively, suggesting that obvious errors are mainly in mountainous area. Besides, the limitation of InSAR technology to generate DEM is analyzed. Our investigation shows that InSAR is an effective tool in geodesy and an important complement to field surveying in some dangerous areas.展开更多
基金This work was supported by Research grant from Institute of Crustal Dynamics,China Earthquake Administration[grant numbers ZDJ2015-15 and ZDJ2013-22]National Natural Science Foundation of China[grant numbers 41104028 and 41204004]and the TerraSAR-X data we used were provided by the DLR in the frame of the General AO project LAN0208.
文摘Yangbajain contains the largest geothermal energy power station in China.Geothermal explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal fluids have been extracted since then,leading to considerable surface subsidence around the geothermal fields.In this paper,InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images.In the case of the TerraSAR-X data,most orbital fringes were removed using precise orbits during the interferometric processing.However,residual orbital ramps remain in some interferograms due to the uncertainties in the TerraSAR-X orbits.To remove the residual orbital ramps,we estimated a best-fit‘twisted plane’for each epoch interferogram using quadratic polynomial models based on a network approach.This method removes most of the long-wavelength signals,including orbit ramps and atmospheric effects.The vertically stratified component(Topography Correlated Atmospheric Delay,TCAD)was also removed using a network approach.If the influence of seasonal frozen ground(SFG)is not taken into consideration,our results show that the subsidence rate around power plant I(the south plant)is approximately 20 mm/yr with a peak of 30 mm/yr.The subsidence rate around power plant II(the north plant)is approximately 10 mm/yr,when accounting for the influence of SFG on the power plant and its surrounding ground surface.Our results show that ground motion is caused by seasonal frozen ground and is strongly related to the temperature change.
文摘Erupting-flow types of geothermal wells in the Yangbajain geothermal field, China, are proposed based on internal energy of geothermal fluids and hydrogeologic-dynamic conditions of wellbore. An erupting-flow model, which is adaptable to the steaming and erupting of flow from wells in the field, has been verified by actual cases.
基金supported by the Basic Scientific Research Special Fund from Institute of Earthquake Science, China Earthquake Administration (02092403 and 0207690224)
文摘Digital elevation model （DEM） can be generated by interferometric synthetic aperture radar （InSAR）. In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite （ERS）-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1：50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared errors （RMSE）, which are used to evaluate error, are about 35, 60, 10, and 15 m in the studied area, mountainous area, basin area and near-fault area, respectively, suggesting that obvious errors are mainly in mountainous area. Besides, the limitation of InSAR technology to generate DEM is analyzed. Our investigation shows that InSAR is an effective tool in geodesy and an important complement to field surveying in some dangerous areas.
