Kearns, and 5 co-authors reported in 2018 that Houston, Texas, is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring. Currently, there are over 200 permanent GPS stations located in the greater Houston area. The need for a consistent and stable reference frame to precisely interpret local ground deformation has become critically important since the 1990s, because of the significant spreading of subsidence. The authors established a stable Houston reference frame, designated Houston16, using publicly available GPS observations (>5 years) from 15 Continuously Operating Reference Stations (CORS) located outside of the greater Houston area. Applications of the reference frame in subsidence and faulting studies are demonstrated in this article. Houston16 is aligned in origin and scale with the International GNSS Reference Frame of 2008 (IGS08).
A 7-parameter method was employed to transform the GPS-derived positional time series from IGS08 to Houston16. The primary product of this study is the seven parameters for transforming Earth-Centered-Earth-Fixed XYZ coordinates from IGS08 to Houston16. The frame stability of Houston16 is approximately 1 mm/year. Houston16 will be updated every few years to mitigate degradation of the frame's stability with time and to synchronize with future updates of the IGS reference frame.
Such stations are important becasue the Houston metropolitan area represents one of the largest subsidence areas in the U.S. The area has been experiencing land subsidence for nearly a century. Accumulated subsidence of over three meters during the past 100 years has been observed within a large area of southeast Houston [2]. Land subsidence in this region is caused primarily by the depressurization of clay lenses in the aquifers due to groundwater withdrawal. The Texas Legislature created the Harris-Galveston Subsidence District (HGSD) in 1975 and the Fort Bend Subsidence District (FBSD) in 1989 to regulate groundwater withdrawal within Harris, Galveston, and Fort Bend counties [3,4]. Prior to the 1990s, subsidence within the Houston area was monitored by conducting leveling surveys and through the use of extensometers. Global Positioning System (GPS) has gradually replaced conventional leveling surveys and has become the primary tool for subsidence monitoring in the Houston area since the 1990s. Accurate longterm monitoring of ground deformation is critical to establishing effective regulations on groundwater withdrawal for the purpose of preventing future subsidence and better securing the local infrastructure, such as bridges, roads, underground pipes and buildings.
For a comprehensive review of subsidence and faulting in the Houston, Texas area, see: Campbell, et al., (2018): http://www.i2mconsultants.com/downloads/corp/JGG-1-015.pdf
Managed & Built by I2M Consulting, LLC | © 2010-
