Study on monitoring land subsidence in mining city based on coherent target small-baseline InSAR

Abstract：Referring to the non-linear surface deformation in coal mining area,the method and effect that coherent target small-baseline InSAR was used to monitor land subsidence in mining city was studied.With the small-baseline coherent targets differential phase time series analysis being the technical cores,the effective coherent targets were maximally extracted by combining the coherence coefficient threshold method with the amplitude dispersion index,and the Delaunay triangulations based on coherent targets were built.The time series phase difference of adjacent targets was analyzed,and interferometric phase sequence was separated one by one under the condition of small baseline,according to the temporal and spatial characteristics of each component in the differential phase composition.Finally,the rate of land subsidence and the amount of accumulative subsidence were extracted effectively.Tangshan City was taken as an example in this study,27 ENVISAT ASAR images of this area acquired between 2004 and 2010 were applied for analysis.The amount and its spatial distribution of land subsidence in urban districts of Tangshan were ascertained,of which the largest average subsidence rate was up to-46.8 mm/a,and the overall subsidence rate was lower than-11 mm/a in the main city zone.Besides,continuous dynamic monitoring results also show the various land subsidence features of mining area at different stages.