IS TUCSON SINKING?

Arizona Department of WaterResources

National Monitoring DayOctober 18, 2002

IS TUCSON SINKING?

IS TUCSON SINKING?

IS TUCSON SINKING?

IS TUCSON SINKING?

IS TUCSON SINKING?

IS TUCSON SINKING?

IS TUCSON SINKING?

LandLandSubsidence Subsidence

Measurement Measurement Using Using

SAR SAR InterferometryInterferometry

ADWR10/2002

What Is SAR Interferometry?

Land Surface

SequentialSatellitePasses

Radar Interferogram 6/1993 to 1/1996

-0.8 in./yr. Max

Air Forcebase

5th St. & Country Club

Downtown

University

Irvington & Park Ave.

Radar Interferogram 11/1993 to 1/2000

-0.8 in./yr. Max

Air Forcebase

5th St. & Country Club

Downtown

University

Irvington & Park Ave.

What Causes Subsidence?

SandsSands ClaysClays

H2OH2O

What Causes Subsidence?

Sands Clays

What Causes Subsidence?

Sands Clays

Over-Burden

Over-Burden

Techniques for Measuring Land Subsidence

• Global Positioning System (GPS) Surveys– Point measurement– Accurate within 1 inch

• Extensometers (measuring sticks in wells)– Point measurement– Very accurate, but only measures part of

aquifer

• SAR Interferometry– Large-scale measurement

– New, requires “ground-truthing”

• Subsidence on the order of INCHES rather than FEET– Eloy, over 15 feet of subsidence by 1980s– Luke Air Force Base, over 10 feet of

subsidence by 1990s

• Subsidence in Tucson is REAL!– Potential damage to infrastructure

– No confirmed effects yet in Tucson

What Does It Mean?

Photo: H.H. Schumann

ELOY, AZ

What Can We Do?

• Use Renewable Supplies

• Conserve Water!

• Continue to Monitor

Arizona Department of WaterResources• http://www.water.az.gov

SPECIAL THANKS TO:

• Center for Space Research, University of Texas– Dr. Sean Buckley

• ADWR Staff– Maurice Tatlow

• California Institute of Technology– Dr. Jakob van Zyl