Is There Deep-Seated Subsidence in the Houston-Galveston Area?

Abstract

Long-term continuous groundwater level and land subsidence monitoring in the Houston-Galveston area indicates that, during the past two decades (1993–2012), the groundwater head has been increasing and the overall land subsidence rate has been decreasing. Assuming that the hydraulic head in the aquifer will reach or exceed the preconsolidation level in the near future, will subsidence in the Houston-Galveston area eventually cease? The key to answer this question is to identify if there is deep-seated subsidence in this area. This study investigated the recent subsidence observed at different depths in the Houston-Galveston area. The subsidence was recorded by using 13 borehole extensometers and 76 GPS antennas. Four of the GPS antennas are mounted on the deep-anchored inner pipes of borehole extensometers. We conclude that recent subsidence (1993–2012) in the Houston-Galveston area was dominated by the compaction of sediments within 600 m below the land surface. Depending on the location of specific sites, the compaction occurred within the Chicot aquifer and part or all of the Evangeline aquifer. No measurable compaction was observed within the Jasper aquifer or within deeper strata. Deep-seated subsidence is not likely occurring in the Houston-Galveston area.

GPS-derived ground deformation (2005–2014) within the Gulf of Mexico region referred to a stable Gulf of Mexico reference frame

“…Both ROD1 and TXCN indicate long-term subsidence. According to our previous studies on the current subsidence in the greater Houston metropolitan area (Kearns et al, 2015;Yu et al, 2014), a rapid-subsidence bowl is forming around The Woodlands area. The Woodlands is a vibrant and fast-growing business and entertainment suburban area located 43 km north of downtown Houston (Fig.…”

“…The near-coast areas could be affected by subsidence and coastal erosion problems (Simms et al, 2013;Williams et al, 1997;Yu et al, 2014). Accordingly, it is preferred that reference stations be located inland rather than within nearcoast areas.…”

“…A recent study conducted by Yu et al (2014) indicated that the subsidence in the Houston metropolitan area is attributed by the compaction of aquifers within about 500 m to the ground surface. Since groundwater usage changes according to the local population and land usage, the subsidence resulting from groundwater withdrawal will vary in space.…”

Geomechanics of subsurface water withdrawal and injection

“…The USGS has been operating 13 borehole extensometers at 11 sites since 1973 for the purpose of observing compaction of aquifers in the whole area. The borehole extensometers, which were designed according to the sliding-joint casing type, span a depth down to 936 m [Yu et al, 2014]. Shanghai is the first city in China where land subsidence was investigated and monitored, being one of the country's most densely populated and developed areas.…”

Introduction to GPS geodetic infrastructure for land subsidence monitoring in Houston, Texas, USA

“…This is primarily attributed to highly precise satellite orbit and clock data provided by the International Global Navigation Satellite System (GNSS) Service (IGS, http://www.igs.org), and new algorithms used to resolve phase ambiguity with a single receiver. The PPP method has attracted broad interests in ground deformation monitoring because of its operational simplicity and high accuracy (e.g., Wang 2013;Wang and Soler, 2014;Yu et al, 2014). Our recent GPS study indicated that the repeatability (RMS) of the daily ambiguityresolved PPP solutions achieved 2-3 mm in the horizontal components and 6-8 mm in the vertical component within the Houston metropolitan area .…”