Low water and sinking ground
Daily Earth Science Geosphere Government Policy Hydrosphere Repost

Sinking ground – Water in the American West

Lake Mead is about 40 percent full, and mandatory water cuts loom on the horizon for the American West. This part of the country is already in a 20-year drought, and farmers need irrigation water to keep their businesses afloat. But groundwater is in short supply, and over-pumping results in sinking ground levels and surface fissures. 

Arizona is at the heart of this water crisis. The State is a signatory to the Colorado River Drought Contingency Plan. This plan stipulates that if water levels in Lake Mead drop to 1,075 feet, then mandatory water cuts must occur throughout the U.S West. If the water level in the lake drops another 25 feet, then the water cuts will kick in. The loss of Colorado river water forces farmers to look to the State’s already-strained groundwater supplies. 

One of the dilemmas faced in Arizona is the lack of a robust regulatory system for groundwater. Groundwater has been pumped from the State’s aquifers for 120 years, and the lack of regulatory controls allowed the aquifers to reach dangerously low levels. However, attempts to establish regulations draw stiff political opposition. Thus problems related to sinking ground now affect 3,400 square miles of the State.

Ground collapse

The first indications of over-pumping are usually water wells that dry up. Below the ground, however, other changes take place. Because the aquifer is primarily composed of water and porous rock, the water stored in the aquifer provides structural support. If enough water is removed, then the aquifer can collapse. The collapse process packs the sand and silt grains closer together, thus leaving less pore space for new water to fill. This process is irreversible, so even if the aquifer fills up again, it can never hold as much water as it initially did.

The effects of aquifer collapse extend to the surface in some areas resulting in sinking ground levels. In Cochise County Arizona, land levels dropped by 10 feet from over-pumping of the local aquifers. Stresses related to the collapse also create cracks and fissures in the earth. About 42 miles of fissures are documented. The surface trenches from these fissures are up to 10 feet wide and 30 feet deep in some cases. The shifting earth also breaks waterlines and destroys building foundations. 

Ironically the drought and groundwater shortages also lead to flooding when the rains do come. Over thousands or millions of years, erosion creates a natural drainage system across the landscape. If a region is relatively flat, then a 10-foot drop in one local area creates a depression that has no natural drainage. When the heavy rains do come, that depression then becomes a temporary lake.

 The playing field is not level

Part of the role of government is the creation of a framework where fair competition and free enterprise thrives. Small businesses rely on antitrust legislation to prevent predatory business practices where large companies with vast financial resources drive them out of the market. In a water-constrained economy, the same regulatory principles apply.

The lack of regulation in Arizona allows large businesses, like the Saudi backed alfalfa growers, to drill deep wells and drain water from underneath the properties of small farmers. Domestic water wells run dry, and small farm irrigation needs go unfulfilled. The deepest pockets are the winners, and the winners take all. 

The current situation is not solely the fault of the large-business interest. It is also the failure of the government to fulfill one of its primary functions and create a level playing field.


ArcheanWeb:

Ogallala Aquifer groundwater, sustaining life (Source: ArcheanWeb) – https://archeanweb.com/2020/02/19/ogallala-aquifer-groundwater-sustaining-life/  Also:

Hot and dry in the Western USA, a megadrought in progress (Source: ArcheanWeb) – https://archeanweb.com/2020/04/21/hot-and-dry-in-the-western-usa-a-megadrought-in-progress/  Also:

Climate change and surface water (Source: ArcheanWeb) – https://archeanweb.com/2020/02/13/climate-change-and-surface-water/  Also:


Sources:

Land fissures, falling earth levels feared with new Arizona water rules (By Jean Lotus; UPI) – https://www.upi.com/Top_News/US/2020/04/30/Land-fissures-falling-earth-levels-feared-with-new-Arizona-water-rules/7591588108728/  Also:

Feature Image: Lake Mead (Modified) – By Raquel Baranow – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=33874549

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.

Leave a Reply

Your email address will not be published. Required fields are marked *