Groundwater Level and Subsidence in the Texas Gulf Coast
Groundwater Level and Subsidence inthe Texas Gulf Coast – USGS Sciencein support of groundwatersustainability By Michael J. Turco, Mark C. Kasmarek, Michaela R. Johnson, and Jason K. Ramage In cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District , and Brazoria County Groundwater Conservation District T B R E O B U D N F D E X A T S S T IC U B S R ID E ST N CE DI
Who is the USGS?• Mission: The U.S. Geological Survey (USGS) serves the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss 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 civilian mapping agency, the USGS collects, monitors, analyzes, and provides scientific understanding about natural resource conditions, issues, and problems. The diversity of our scientific expertise enables us to carry out large-scale, multi-disciplinary investigations and provide impartial scientific information to resource managers, planners, and other customers.
GAMEPLAN• Introduction• Groundwater level – Hydrogeology – Summary results of 2011-2012 survey• Subsidence – Clay-compaction and Subsidence – Methods of Measure – Recent subsidence• Modeling• Summary
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 a well by well basis• Three primary water bearing units within the Gulf Coast Aquifer System (Chicot, Evangeline, and Jasper)• Water-levels measured and quality-assured following USGS documented methods• All maps peer-reviewed and published annually
C.I. 20 ft -220 to 0 2000-2012 Jasper Water Level Change
SUBSIDENCE• Subsidence associated with shallow fluid withdrawal in the TX Gulf Coast Region has been 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 of subsidence has occurred along the Houston Ship Channel since 1917
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
SIM Sheet 15Borehole Extensometer Locations, Texas, USA
Recent Subsidence Estimated using PAM-GPS Data
PAM-GPS Horizontal and Vertical Velocity field
Estimated Subsidence usingInSAR analysis and PAM-GPS Data
Estimating future subsidence• Requires substantial historical information• PRESS Models – developed by FUGRO Inc. to predict subsidence based detailed local hydrogeologic data and predicted changes in water level• MODFLOW Model – developed by USGS; multiple evolutions over the last 25+years; simulates water- level and subsidence regionally
Summary• Groundwater data collected today, although maybe used for an immediate resource 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 data set used by multiple agencies to manage the groundwater resource and minimize subsidence in the Houston area.• Subsidence monitoring as evolved over the last 35 years, multiple approaches to evaluating past and current subsidence has yielded a strong data set used to calibrate models that can then predict future subsidence based estimated water needs and aquifer response.
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, Texas Ph: 936-271-5300 http://tx.usgs.gov