Land subsidence in Houston, Texas, measured by radar interferometry and constrained by extensometers

We present results from a radar interferometry study over the Houston-Galveston, Texas Gulf Coast region. From the nearly 60 potential interferograms considered, an atmospheric artifact assessment is performed and a tractable set of interferograms selected for detailed processing and error analysis. The subsequent interferogram time series spanning 1996 - 1998 is constrained by coincident extensometer data with root-mean-square error less than 2.5 mm. The interferogram time series confirms that historic subsidence in east Houston has stopped. Consistent with current groundwater use patterns, broad-scale subsidence bowls are observed in west and northwest Houston, where maximum subsidence rates are in excess of 2 and 4 cm yr(-1), respectively. Linear interferogram phase signatures associated with approximately 1 cm of differential subsidence across faults, including the Long Point fault in northwest Houston, are observed. Near the Seabrook extensometer, a hereto-unidentified subsidence bowl with a maximum subsidence rate in excess of 3 cm yr(-1) is revealed. This study demonstrates that when used in conjunction with a set of traditional geodetic measurements, radar interferometry can measure the spatial and temporal evolution of urban land subsidence within even the most challenging of environments.