Land Subsidence in Taiyuan, China, Monitored by InSAR Technique With Multisensor SAR Datasets From 1992 to 2015

Abstract

Taiyuan city has been suffering significant subsidence during last two to three decades, mainly due to the effects of groundwater withdrawal and urban construction. The purpose of this study is to map the spatial-temporal variations of land subsidence over Taiyuan and analyze the causes of the observed deformations by using the interferometric point target analysis (IPTA) technique with multisensor SAR datasets during 1992 and 2015. The InSAR-derived deformations are then compared to the leveling measurements and groundwater data. The observed deformation based on ERS-1 datasets has mapped regional subsidence rate ranging from 30 to 60 mm/a in the northern and central Taiyuan from 1992 to 1993. InSAR measurements from Envisat ASAR, TerraSAR-X, and Radarsat-2 data reveal land subsidence rate up to 80 mm/a in the southern suburb during 2009 to 2015, whereas a rebound rate more than 10 mm/a in northern Taiyuan from 2004 to 2005. The time series deformation maps from 2009 to 2010 present slight nonlinear periodic variations, which might be caused by the seasonal groundwater fluctuations. The observed InSAR results indicate that the pattern of ground deformation is nearly concentric around locations of intense groundwater withdrawal, and the spatial extent of the subsiding area has been shrinking and moving toward the central and southern Taiyuan after 2003. Furthermore, differential subsidence rates are identified on both sides of Tianzhuang fault from observed deformation maps during the period of 2009–2010, 2012–2013, and 2014–2015, which could be explained that the fault acts as the barrier to the groundwater flow. Our results could provide significant evidence to serve the decision-making on land subsidence mitigation in Taiyuan, China.