Ground Deformation Mapping of Houston-Galveston, Texas Using InSAR Time-Series Analysis

Thursday, 18 December 2014
Feifei QU1, Zhong Lu1, Gerald W Bawden2 and Jin Woo Kim1, (1)Southern Methodist University, Dallas, TX, United States, (2)US Geological Survey, Sacramento, CA, United States
Houston-Galveston region in Texas has been subsiding due to the combined effects of groundwater withdrawal, hydrocarbon extraction, soil compaction, and active faulting. This human- and partially nature-induced ground deformation has gradually threatened the stability of urban infrastructure and caused the loss of wetland habitat along the Gulf of Mexico. Interferometric synthetic aperture radar (InSAR) exploiting multiple SAR images has the capability of obtaining ground motions in high spatial resolution over large coverage. In this study, ERS-1/2 (1993-2000), ENVISAT (2004-2010), and ALOS (2007-2011) datasets are used to unravel the characteristics of ground deformation from 1993 to 2011 over the Houston-Galveston area. The persistent scatterer InSAR (PSInSAR) time-series analysis technique is employed to estimate the spatial and temporal variations of ground motions during 20 years. The ERS-1/2 PSInSAR products have measured subsidence (up to 5 cm/yr) in the northwest Houston area as well as a slight uplift (1 cm/yr) in the southeast region from 1993 to 2000. The subsidence rate (up to 2 cm/yr) between 2004 and 2011 has been obtained from ENVISAT and ALOS data. Our results indicate that the pattern of ground deformation was nearly concentric around the location of intense groundwater withdrawal and the subsiding area has been shrinking and migrating toward the northeast after 2000. In addition, an approximately 2 cm of differential subsidence across faults are observed. Presence of faults can induce localized surface displacements, aggravate localized subsidence, discontinue the integrity of ground water flow, and limit the horizontal spread of subsidence funnels. Finally, our long-term measurement of ground deformation has also been validated by GPS observations in study area.