In Arizona’s Willcox Basin, the land is quietly collapsing as years of groundwater pumping take their toll beneath the desert surface. Scientists are uncovering just how severe the sinking has become and why even recent rains can’t undo the damage.
Credit: Brian Conway
Groundwater extraction for irrigation is leading to rapid subsidence, though effective state management could help slow the process.
In Arizona’s Willcox Basin, located just over an hour east of Tucson, the ground is literally breaking apart. Cracks spread across the surface, wells are running dry, and unusual flooding appears after heavy rains. The reason is straightforward: large-scale farms are extracting vast amounts of groundwater for irrigation, causing the water table to drop and the land itself to subside.
“For a long time,” says Dr. Danielle Smilovsky, a geospatial research scientist at the Conrad Blucher Institute, “there were no water regulations there.”
Smilovsky recently presented new findings at GSA Connects 2025 in San Antonio, Texas, detailing how much the region has sunk. Her five-year study, covering 2017–2021, used satellite observations to track subtle ground movements. The data revealed that some parts of the basin are sinking by as much as six inches per year—nearly three feet over the study period. Since the 1950s, the ground in some areas has dropped by up to 12 feet. The Willcox Basin now shows the fastest rate of subsidence in Arizona, although the issue extends across much of the state.
Why the Ground Is Collapsing
This sinking happens when groundwater is pumped out faster than it can naturally recharge. As water levels decline, the tiny spaces between underground sediment grains lose the pressure that once kept them open. Water normally acts like a cushion, supporting the surrounding material and balancing the weight of everything above. When that pressure disappears, the sediments compact, and the surface gradually sinks.
“Over time, those pore spaces that were once being held open by water pressure start to collapse,” says Brian Conway, a geophysicist at the Arizona Department of Water Resources, “and that causes the overlying surface to sink because of the compaction that’s happening in the subsurface.”
The Life of Earth
https://chuckincardinal.blogspot.com/
No comments:
Post a Comment
Stick to the subject, NO religion, or Party politics