Current Ground Motions in Montgomery, West Liberty, and Northern Harris Counties Derived from Continuous GPS Motions



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The greater Houston area has been adversely affected by land subsidence possibly more than any other area in the United States. Houston and its surrounding areas have been suffering frequent infrastructure damage associated with faulting and land subsidence for almost a century. Currently, land subsidence in downtown Houston and the southeastern region of the Houston metropolitan area has nearly ceased (< 3 mm/ year) as a result of enforced groundwater regulations. Slight land rebound has been observed along the Houston Ship Channel area since 2005. However, GPS observations indicate that subsidence rates over about 2 cm/year are occurring in the southern part of Montgomery county and the northwest and central northern part of Harris County. Montgomery County is one of the areas that is suffering from severe damage resulting from land subsidence and local faulting. This study investigated the on-going vertical ground motions recorded by GPS and ground water level changes recorded by wells within Montgomery County, northern Harris County, and west Liberty County. The U.S. Geological Survey (USGS), Lone Star Groundwater Conservation District (LSGCD), Harris Galveston Subsidence District (HGSD), University of Houston (UH), and other local agents have been continuously monitoring ground water and land subsidence in this area for over 10 years. Through the use of USGS ground water monitoring wells and permanent GPS stations, this study explored the long-term interaction between fluctuation of groundwater and land subsidence. GPS stations recorded subsidence rates that range from 0.082 cm/year to -2.739 cm/year and provides fundamental information for predicting future land subsidence, which is critical for properly implementing a plan for adjusting the ground water regulations within the foreseeable future.



GPS, HoustonNET, Subsidence