Skip to main content
Arizona Department of Water Resources Logo

Arizona Department of Water Resources

Protecting & enhancing Arizona’s water supplies for current and future generations.

Search form

  • About Us
    • ADWR Strategic Plan and Annual Reports
    • Mission - Values
    • History of the Department
    • Arizona Water Facts
    • Small Business Bill of Rights
    • Career Opportunities
  • How Do I?
    • Apply For
      • Change of Ownership
      • New Well
      • Permit
      • Statement of Claimant, Assignments, Amendments
      • Well Driller's License
      • Funding Opportunities
    • Locate
      • A Surface Water Right
      • A Well
      • Statement of Claiment
    • Get Data
      • AAWS Interactive Map
      • ADWR Dictionary
      • GIS Data Center
      • Data Queries
      • Groundwater Levels
      • Imaged Records
      • Land Subsidence in Arizona
      • Wells 55
      • Wells Data
    • Pay For
      • Annual Report Fee
      • Invoice
    • Report
      • Complaint or Concerns
      • Water Use
      • Share or Report a Water Level - 3rd Party Water Level Data Portal
      • Report Dry Well Data
      • Civil Rights
    • Find Info On
      • Arizona Reconsultation Process
      • Conservation
      • Colorado River Shortage Preparedness
      • Drought Contingency Planning
      • Laws, Rules, & Policies
      • Public Records Request
      • Pinal Groundwater Supply Updates
      • Public Meetings
      • Public Notices
      • Water Levels
      • Wells
      • Legislative Affairs
      • Lower Hassayampa Sub-Basin Groundwater Model Report
  • ADWR News
    • ADWR News
    • Blog
    • Podcasts
    • Videos
    • Archive
  • Home
  • Programs
    • Active Management Areas
    • Adjudications
    • Assured and Adequate Water Supply
    • Colorado River Management
    • Community Water Systems
    • Conservation
    • Dam Safety
    • Drought
    • Engineering
    • Floodplain Management and Flood Warning
    • Governor’s Water Policy Council
    • Hydrology
    • Irrigation Non-Expansion Area
    • Laws, Rules, & Policies
    • Legislative Affairs
    • Management Plans Work Group
    • Recharge
    • Statewide Planning
    • Rural Programs
    • Surface Water
    • Wells and Permitting
    • Water Banking Authority
    • Water Protection Fund
  • Online Services
    • Annual Water Use Report
    • Application Forms
    • Hydrology Publications (eLibrary)
    • Land Subsidence Maps
    • ADWR Live Queries and Reports
    • Recharge Long-Term Storage Credit Balance
    • Imaged Records
    • eNOI
    • Online Notice of Well Capping
    • Pump Installation Completion Report
    • Online Driller's Log
    • Online Payments
    • Change of Ownership
    • Assured & Adequate Water Supply Pending Applications
    • Water Atlas
    • Surface Water Online Notices
    • Interactive Maps
      • Assured and Adequate Water Supply Interactive Map
      • Community Water System (CWS) Interactive Map
      • Groundwater Site Inventory (GWSI)
      • Well Registry Data (55)
      • GIS Data
  • Contact Us
    • Concerns
    • Human Resources
    • Contact Us
    • Public Records Request

Ebbing Away

Earth Fissures

Ebbing Away

Ebbing Away
Published: January 12, 2017

The problem of land subsidence in Arizona – the lowering in elevation of land-surface levels, largely the result of groundwater extraction – is a decidedly mixed bag, the Arizona Department of Water Resources is discovering.

Thanks to decreased groundwater pumping in the Phoenix and Tucson Active Management Areas, for example, subsidence rates in many areas of those AMAs have decreased between 25 and 90 percent compared to rates in the 1990s.

That is just one of the major findings of the department’s recent “Land Subsidence Monitoring Report No. 3,” released earlier this month.

And it’s the news from the happy side of the bag.

On the opposite side, land subsidence statewide is proving to be an increasingly serious challenge that is causing problems for infrastructure in some areas. And it is proving to be a headache even in certain parts of active-management areas.

Monitoring for subsidence

As the report describes, Water Resources first began monitoring for subsidence in the eastern areas of the Valley and around Luke Air Force Base in the west after numerous “non-exempt” wells – that is, wells that draw up groundwater at rates faster than 35 gallons per minute – were installed starting in 1997.

Historically, land levels in those areas have dropped at significant rates, the recent report finds.

The problems caused by land subsidence do not go away simply by fixing cracked foundations, reconnecting broken pipelines or repairing roadways.

Subsidence is caused by the collapse of open-pore spaces in subsurface aquifers, an unseen water-storage catastrophe in the making. When the open-pore spaces of aquifers fully collapse, they collapse permanently, in most cases.

“Land subsidence is a regional problem for some groundwater basins in the state and may continue to be an ongoing problem,” said Brian Conway, who prepared the report on behalf of Water Resources.

Arizona Department of Water Resources's Brian Conway, Supervisor for the Geophysics/Surveying Unit

 “Even if sustainable, safe-yield groundwater withdrawal occurred, residual land subsidence would continue until the groundwater levels recover -- and/or the open pore-spaces in the sub-surface fully collapse.”

As one would expect, the Water Resources report finds that subsidence is most active in regions outside the active-management areas – that is, in areas where groundwater pumping is unregulated.

Land subsidence has resulted in more than 160 miles of earth fissures. The Arizona Geological Survey maps all the earth fissures throughout the state. The Geological Survey analysts provide Water Resources with the data from their research.

The Geological Survey and Water Resources analysts have found that the Willcox Groundwater Basin in southeastern Arizona is the most active area for forming new earth fissures.

Southeastern Arizona is one of the regions most severely impacted by drought. The area also has seen substantial increases in farming operations that rely on mined groundwater.

The Willcox Basin is outside the reach of the state’s Groundwater Management Act of 1980, which regulates groundwater extraction in active-management areas. According to the report, new earth fissures in the area are impacting roads, highways, power lines and a pipeline.

The report observes that other non-AMA regions of the state also have seen considerable increases in their rates of earth subsidence, notably parts of the McMullen Valley Basin and the San Simon Valley Sub-basin. Both of those regions have seen increased agriculture activity in recent years that is reliant on mined groundwater

Earth FissureThe subsidence mapping process employs the latest radar technology -- known as “InSAR,” or satellite-based synthetic aperture radar.

The introduction of the InSAR technology has proved to be a game-changer in terms of the state’s ability to accurately track the development of subsidence over time.

Water Resources was awarded a $1.3 million grant from NASA in 2002 that kicked off a three-year effort to integrate the InSAR system into Arizona’s subsidence-monitoring programs.

The program now has 14 different partners in the effort whose financial support allows the department to fund the InSAR data collection.

The side-looking, self-illuminating, radar-imaging system has helped Water Resources develop an extensive library of scenes, covering an area greater than 150,000 square miles.

With the InSAR data, Water Resources has identified more than 26 individual land subsidence features around the state, collectively covering more than 3,400 square miles.

“The InSAR data is a huge part of our monitoring efforts now,” said Conway.

“We are able to cover large areas with the data and are able to see millimeter changes of deformation at a very high resolution.”

waves.png

Waves icon
  • Overview
  • News Articles
  • News Blog
  • Audio Podcasts
  • Video

 

telephone-icon.png

Telephone icon
  • [email protected]
  • (602) 771-8500

 

Follow Us

Contact Info

Arizona Department of Water Resources
1110 W Washington Street Suite 310
Phoenix, AZ 85007
Find in Google Maps
Phone: 602.771.8500 | Fax: 602.771.8689
File a complaint

Newsletter Subscription

Sign up to get breaking news and information about Arizona’s water industry!

Lists*

© 1980 - 2023 Arizona Department of Water Resources - Statements & Policies | Site Map