InSAR uses radar data from satellites to measure and monitor ground deformation over large areas with high precision. It works by comparing phase differences between radar images taken at different times. Recent satellite missions like Sentinel-1 and upcoming NISAR provide free and frequent data. Case studies in Texas show InSAR can detect subsidence and uplift related to oil/gas production, wastewater disposal and other human and natural causes at rates of centimeters per year over areas of 100 km squared with resolutions of tens of meters. Available data and analysis software allow low-cost, rapid evaluation of deformation trends.

1. 1
Application of Satellite Data to Rapidly and Effectively
Evaluate Rates of Deformation
Presented by:
June 9, 2021
Presented To:
Dr. Zhong Lu & Dr. Feifei Qu
Steve Young & Hai Pham
Texas Alliance of Groundwater Districts

2. 2
Outline
• Description of InSAR
– How it works
– Satellites (past, present, future)
• Applications
– Houston Area
• Harris, Fort Bend, Wharton & Matagorda counties
– West Texas
• Winkler, Ward, Pecos counties
• Summary

3. 3
Radar - Radio Detection and Ranging
In its simplest form, a radar operates by:
• Sending a signal into space - when
the signal encounters an object
then some of the signal redirected
back to the radar antenna
• Receiving the “echoed” signal back
from the encountered objects
Precise timing of the echo delays allows
determining of the distance and or “range”

4. 4
Synthetic Aperture Radar (SAR)
Radar that bounces a microwave radar signal off the
Earth’s surface to detect physical properties
– Involves a radar antenna moving over target
– Creates two and three-dimensional images of objects
Microwave
Bands X-band C-band L-band
Reflected by
branches
Reflected
by leaves
Reflected
trunks &
ground
Improved Performance for measuring ground surface

5. 5
The interferogram used to create surface of land deformation:
• Over areas of ~100 km x 100 km
• with a horizontal resolution of tens of meters
• with vertical centimeter to sub-centimeter precision
under favorable conditions.
Interferometric SAR - InSAR
•Interferometric synthetic aperture
radar (InSAR) combines information
from two or more radar images of the
same area acquired from at different
times and “interferes” (differences)
them, resulting in maps called
interferograms that show ground
displacement (range change) between
to time periods

6. 6
InSAR: Data Analysis
• Factors
– Topography conditions
– Atmosphere conditions
• clouds
• humidity
– Satellite conditions
• Calculations
– time of travel
– amplitude reduction
– phase shift

7. 7
Remote Sensing: Polar Orbit
passing over Gulf Coast
in evening
passing over Gulf Coast
in morning

8. 8
Radar Satellites
• Sentinel-1A/B are the first set of radar satellites that provide free data;
• Future Missions: NISAR (USA) – 2023; ALOS-4 (Japan) – 2022; Canada, China, Argentina, DLR,
ESA, ….
Japanese
JERS-1
Japanese ALOS-1 ALOS-2
L-Band
German TerraSAR-X
German TanDEM-X
Italian COSMO-SkyMed
X-Band
1992 1995 2002 2006 2007 2008 2010 2014
European ERS-1
European Envisat Sentinel-1A/B
Canadian Radarsat-1 Canadian Radarsat-2
C-Band
European ERS-2
KOMPSAT-5

9. 9
Satellite GAME Changer: NISAR
• Joint mission with U.S. and India
• Available in 2022-2023
• L-band (NASA) / S-band (ISRO)
• 12 revisit days
• ~10 m resolution
• Open data and software – 1 to 2
days after observations
Temporally-dense high-resolution SAR satellite datasets such as NISAR
will provide invaluable opportunities to detect deformation caused by
natural and anthropogenic hazards.
http://nisar.jpl.nasa.gov/ *ISRO – India Space Research Organization

10. 10
Houston Area
Fault traces based on InSAR
(black dashed lines);
Fault traces based on LiDAR
(white lines); (Qu et al., 2019)

11. 11
Wharton County
(Young et al., 2020)
Deformation is average over 2016 to 2019
Sentinel 1 A/B Ascending
Sentinel 1 A/B Ascending

12. 12
Comparison Between Continuous Operating Reference
Stations (CORS) and InSAR Deformation Rates
-3.5 mm/yr
-1.2 mm/yr
-2.2 mm/yr
• Ascending data has 75 to
80 data points from 2016
to 2019
• Slope of blue line
provides deformation
rate
(Young et al., 2020)

13. 13
Continuous Operating Reference Stations (CORS)
CORS
– More than 1,400 sites
– Multi-agency cooperative endeavor
involving hundreds of organizations
– Managed by NOAA/National Geodetic
Survey
– Satellites (past, present, future)

14. 14
Rationale for Low Subsidence Rates: Water Levels
1) Water levels have been relatively
stable the last twenty years at 86
well locations
2) Average for recent annual
productions lower than 1965-1965
averages
(Young et al., 2020)

15. 15
Matagorda County
(Young et al., 2021)
Deformation is average over 2007 to 2010
ALOS-1

16. 16
Winkler County
Measured uplift likely
caused by wastewater injection
(Kim & Lu., 2021)

17. 17
Winkler County
Kim, Lu, Kaufmann, 2018.
• Wink Sink #1 – collapsed 1980 Wink Sink #2 – collapsed 2002
• (average about 5 cm/yr from Oct. 2015 to Feb 2017)
• Greatest subsidence of 53 cm/yr one km east of Wink Sink #2
One Cycle:

18. 18
Ward County
Kim & Lu, 2018.
• Oil & gas are produced from
Yates and Queen Formations at
depths of ~3,000 ft
• Miscible CO2 is injected into the
formations
North Ward Estes Field

19. 19
Pecos County
Kim, Lu, Kaufmann, 2018.
• The neighboring region of Boehmer
Lake (F,G) is subsiding (5 cm for 2.5
years).
• The area along FM 1053 road (H,I)
is subsiding at a rate ~10 cm/year.
• The area around the abandoned oil
(J,K)wells is also subsiding (13 cm
for 2.5 years).
• The subsidence is occurring in
temporally linear fashion regardless
of any seasonal effects.
• High salinity of channels along the
Pecos River near Imperial suggests
that the surface and underground
water interact with the subsurface
salt deposit (Jensen et al., 2006;
Miyamoto et al., 2008)

20. 20
Process for Sinkhole Formation
Kim, Lu, Kaufmann, 2018.

21. 21
InSAR Summary
• Significant advances recently with obtaining and
processing data
• Used to create Surface of Land Deformation
• Areas of ~100 km x 100 km
• Horizontal resolution of tens of meters
• Vertical resolution is centimeters and subcentimeters under
favorable conditions
• Data Availability
– Considerable amount of data can be downloaded at no
costs
– NISAR will be 2022-2023
• Software Availability
– Multiple free packages availability
– Results can be highly sensitive to methodology

22. 22
QUESTIONS ?
Questions ?