An Interferometric SAR Study of Subsidence in Houston, Texas

Houston subsidence dates back nearly a century and continues to the present. In areas of greatest groundwater extraction, this subsidence has reached 3 m. At benchmarks west of Houston, 1987 subsidence rates ranged from 3.1 to 7.6 cm/yr. Present subsidence rates in West Houston are on the order of 5 cm/yr.

Houston Subsidence Measured By the Differential INSAR Technique
The Houston area is undergoing subsidence rates that should be observable using the INSAR technique with the greatest subsidence rates occurring in the center of Houston. Research has shown that the interferometric phase remains well correlated in urban areas over long periods of time [Dixon (editor), 1995]. This advantageous characteristic of urban areas will increase the likelihood of witnessing subsidence in all parts of the Houston area (one simply waits long enough to see the surface displacement) as well as allowing both short term and long term subsidence rates to be determined from a time series of subsidence displacements fields.

INSAR-derived Houston subsidence measurements are complementary to the NGS/HGCSD GPS network subsidence measurements. Specifically, the INSAR-derived Houston subsidence measurements will provide a more spatially dense set of subsidence measurements while using the GPS network measurements as tie points. Spaceborne repeat-pass differential interferometry has the potential of providing new insight into the short term and long term subsidence of Houston every time a SAR satellite passes overhead.