USGA Science in support of groundwater sustainability. Presented by Michael J. Turco, Mark C. Kasmarek, Michaela R. Johnson, and Jason K. Ramage. at the TWCA Fall Conference 2012 www.twca.org

1. Groundwater Level and Subsidence in
the Texas Gulf Coast – USGS Science
in support of groundwater
sustainability
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

2. 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 Nation's 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.

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 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

7. Hydrogeology

8. 2012 Chicot Aquifer Network

9. 2011-2012 Chicot Water Level Change

10. Explanation
Decline
No Change
Rise
C.I. 20 ft -100 to 200
1977-2012 Chicot Water Level Change

11. Hydrogeology

12. 2012 Evangeline Aquifer Network

13. 2011-2012 Evangeline Water Level Change

14. Explanation
Decline
No Change
Rise C.I. 20 & 40 ft -360 to 260
1977-2012 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 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

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 15
Borehole Extensometer Locations, Texas, USA

23. Extensometer

24. Harris County
Liberty County
Chambers County
Fort Bend County
Brazoria County
Galveston County
Updip Extensometer Data

25. Harris County
Liberty County
Chambers County
Fort Bend
County
Galveston
County
Brazoria County
SIM 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 using
InSAR analysis and
PAM-GPS Data

31. 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

32. Estimating Future subsidence

33. 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.

34. Water Use and Water Availability – USGS Science in support of
groundwater 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