1. Groundwater Level and Subsidence inthe Texas Gulf Coast USGS Sciencein support of groundwatersustainabilityBy Michael J. Turco, Mark C. Kasmarek, Michaela R. Johnson, and Jason K. RamageIn cooperation with theHarris-Galveston Subsidence District, City of Houston, Fort BendSubsidence District, Lone Star Groundwater Conservation District , and Brazoria County Groundwater Conservation DistrictT BR EO BUDNFDE XATSS TIC UBS RID E ST N CE DI

2. Who is the USGS? Mission: The U.S. Geological Survey (USGS) serves the Nation by providingreliable scientific information to describe and understand the Earth; minimizeloss of life and property from natural disasters; manage water, biological,energy, and mineral resources; and enhance and protect our quality of life. As the Nations largest water, earth, and biological science and civilianmapping agency, the USGS collects, monitors, analyzes, and providesscientific understanding about natural resource conditions, issues, andproblems. The diversity of our scientific expertise enables us to carry outlarge-scale, multi-disciplinary investigations and provide impartial scientificinformation to resource managers, planners, and other customers. 3. GAMEPLAN Introduction Groundwater level Hydrogeology Summary results of 2011-2012 survey Subsidence Clay-compaction and Subsidence Methods of Measure Recent subsidence Modeling Summary 4. Study Area 5. Houston Climate 2011 6. GROUNDWATER LEVELS USGS measures water-level in about 800 wells annually Specific criteria is followed when adding a well to the network;always looking to expand network Measured data are compared over several temporal ranges on awell by well basis Three primary water bearing units within the Gulf Coast AquiferSystem (Chicot, Evangeline, and Jasper) Water-levels measured and quality-assured following USGSdocumented methods All maps peer-reviewed and published annually 7. Hydrogeology 8. 2012 Chicot Aquifer Network 9. 2011-2012 Chicot Water Level Change 10. ExplanationDeclineNo ChangeRiseC.I. 20 ft-100 to 2001977-2012 Chicot Water Level Change 11. Hydrogeology 12. 2012 Evangeline Aquifer Network 13. 2011-2012 Evangeline Water Level Change 14. ExplanationDeclineNo ChangeRiseC.I. 20 & 40 ft -360 to 2601977-2012 Evangeline Water Level Change 15. Hydrogeology 16. 2012 Jasper Aquifer Network 17. 2011-2012 Jasper Water Level Change 18. C.I. 20 ft -220 to 0 2000-2012 Jasper Water Level Change 19. SUBSIDENCE Subsidence associated with shallow fluidwithdrawal in the TX Gulf Coast Region hasbeen studied by USGS and others since the~1950s Goose Creek Oil Field first documented case(Pratt and Johnson, 1926) USGS has estimated that about 15 feet ofsubsidence has occurred along the HoustonShip Channel since 1917 20. Clay Compaction 21. How do you measure subsidence? Borehole extensometer Modified deep well used in Houston, California, China, Mexico 1st order leveling Reoccupy benchmarks from Waco to Galveston PAM-GPS network Sub-cm accuracy at established benchmarks reoccupied periodically over time Historical LIDAR comparisons Comparison of recent LIDAR data and historical topography InSAR Satellite based method of detecting subtle land-surface change over large areas 22. SIM Sheet 15Borehole Extensometer Locations, Texas, USA 23. Extensometer 24. Harris County Liberty County Chambers CountyFort Bend CountyBrazoria CountyGalveston County Updip Extensometer Data 25. Harris County Liberty County Chambers County Fort BendCounty Galveston County Brazoria CountySIM Sheet 16 Pasadena and Clear Lake Extensometer Data 26. Estimated Subsidence 1915-2001 27. PAM-GPS Land Surface Elevation Change 28. Recent Subsidence Estimated using PAM-GPS Data 29. PAM-GPS Horizontal and Vertical Velocity field 30. Estimated Subsidence usingInSAR analysis andPAM-GPS Data 31. Estimating future subsidence Requires substantial historicalinformation PRESS Models developed byFUGRO Inc. to predict subsidencebased detailed local hydrogeologicdata and predicted changes inwater level MODFLOW Model developed byUSGS; multiple evolutions over thelast 25+years; simulates water-level and subsidence regionally 32. Estimating Future subsidence 33. Summary Groundwater data collected today, although maybe used for an immediateresource need, become more valuable as time moves on. Without data today,the ability to evaluate the effects of changing water use, regulatory strategies,or new water sources is greatly diminished. A long history of collaboration and data collection as resulted in a robust dataset used by multiple agencies to manage the groundwater resource andminimize subsidence in the Houston area. Subsidence monitoring as evolved over the last 35 years, multiple approachesto evaluating past and current subsidence has yielded a strong data set used tocalibrate models that can then predict future subsidence based estimated waterneeds and aquifer response. 34. Water Use and Water Availability USGS Science in support ofgroundwater sustainability with case study in Houston, Texas,USA QUESTIONS? CONTACT: USGS Texas Water Science Center Gulf Coast Program Office The Woodlands, TexasPh: 936-271-5300 http://tx.usgs.gov