Land Subsidence Estimation With Tide Gauge and Satellite Radar Altimetry Measurements Along the Texas Gulf Coast, USA

A double-difference (DD) method was used to estimate vertical land motion (VLM) at 26 tide gauge (TG) sites with record lengths of at least ten years across the Texas Gulf Coast, USA, between 1993 and 2020. In the method, the first difference was conducted by coupling nearby correlated TG stations to remove sea-level variability for both TG and satellite radar altimetry (SRA) data. Upon completion of the first difference, a second difference was performed by subtracting between TG and SRA data. The results obtained from the DD method were compared against that of: 1) a single-difference (SD) method through subtraction between measurements from TG and SRA and 2) a global navigation satellite system (GNSS) precise point positioning (PPP) method. The results showed that the DD method improved the performance of VLM estimation with an uncertainty below 1.0 mm/yr at most TG stations. Meanwhile, the estimated VLM trends acquired from the DD method correlated better to that of the ground-truth GNSS PPP solutions than the SD method. The DD method possesses great potential to discover VLM knowledge, particularly along coastal regions where other techniques such as GNSS and interferometric synthetic aperture radar (InSAR) are of impaired estimation capability.