A decade of land displacement evolution over the Gulf Coast of United States using multiple InSAR data sets

Abstract:

Ground displacement has occurred in many parts of the Gulf Coast. Complicated geological composition and high intensity of exploitation of underground fluids along the Gulf Coast have changed hydraulic properties of the underground aquifer system, reactivated faults and generated fissures, caused extensive damages to infrastructures, and increased seawater intrusion, the loss of wetland habitat and more frequent flooding. Aiming at investigating land surface deformation development of Gulf Coast, we applied multi-temporal InSAR technique with 33 paths of L-band ALOS PALSAR images from 2007 to 2011, a dozen paths of Sentinel-1A/B during 2015 and 2019, as well as hundreds of Envisat, ALOS2 and COSMO-SkyMed scenes. We produced, for the first time, yearly displacement maps over the Gulf Coast from Mexico to northern Florida. Deformation velocities from all tracks were mosaicked together to produce seamless maps of land displacement over about a wide area of ~500,000 km², with an average standard deviation of ~0.8 cm in the overlap area between tracks. InSAR time-series analysis was further combined with GPS data to separate tectonic deformation signal from human-induced local deformation to enhance our understanding of deformation processes. Generally, the Gulf Coast is fairly stable except for the broad-scale subsidence, such as Houston region (up to 4 cm/yr), New Orleans (about 2 cm/yr) and some localized uplift/subsidence cones over the disposal, injection or oil/gas production wells. Furthermore, we constructed annual deformation maps over the Houston region from 2004 to 2019 to further study the combined effects of climate changes on coastal city flooding, with a focus on the 2011-drought and 2017 hurricane Harvey events. Multiple SAR datasets have been explored to estimate the long-term rates of ground subsidence before and after these events, and our investigation will help successfully understand the impacts of drought and flooding on the long-term land stability over the region.