Satellite InSAR data show parts of Arizona’s Willcox Basin subsiding faster than 6 inches (15 cm) per year, with nearly 3 feet (1 m) lost from 2017–2021 and up to 12 feet (3.6 m) since the mid-20th century. Researchers attribute the decline to intensive groundwater pumping for agriculture, which compacts subsurface sediments and permanently reduces aquifer storage. Heavy rains in 2022–2023 provided only temporary relief, and policymakers designated the basin an Active Management Area in 2024 to limit extraction. Experts say regulation may slow subsidence but is unlikely to stop it entirely.
Satellite Data: Parts of Arizona’s Willcox Basin Are Sinking More Than 6 Inches Per Year
Satellite InSAR data show parts of Arizona’s Willcox Basin subsiding faster than 6 inches (15 cm) per year, with nearly 3 feet (1 m) lost from 2017–2021 and up to 12 feet (3.6 m) since the mid-20th century. Researchers attribute the decline to intensive groundwater pumping for agriculture, which compacts subsurface sediments and permanently reduces aquifer storage. Heavy rains in 2022–2023 provided only temporary relief, and policymakers designated the basin an Active Management Area in 2024 to limit extraction. Experts say regulation may slow subsidence but is unlikely to stop it entirely.
08:56 PM, 11/13/2025Environment
Satellite data reveal rapid land subsidence in Arizona's Willcox Basin
Satellite measurements show that portions of Arizona’s Willcox Basin are subsiding at rates exceeding 6 inches (15 cm) per year — the fastest land-surface decline recorded in the state. Using interferometric synthetic aperture radar (InSAR), researchers detected nearly 3 feet (about 1 m) of vertical loss in some locations between 2017 and 2021, and prior studies report up to 12 feet (3.6 m) of cumulative subsidence since the mid-20th century.
What's causing the ground to sink?
Scientists link the sinking primarily to intensive groundwater pumping for agriculture. Groundwater fills pore spaces between sediment grains beneath the surface; when that water is removed, those pore spaces can collapse and the sediment compacts. That compaction causes the ground above to settle, and because the pores have physically compressed, the loss of storage capacity in the aquifer is effectively permanent.
"Over time, those pore spaces that were once being held open by water pressure start to collapse," said Brian Conway, a geophysicist at the Arizona Department of Water Resources (not involved in the new study). "That causes the overlying surface to sink because of the compaction that's happening in the subsurface."
Evidence from satellites
Research presented on Oct. 20 at The Geological Society of America Connects 2025 in San Antonio used InSAR to measure tiny changes in surface elevation by comparing repeated satellite passes. Averaging multiple measurements makes it possible to detect centimeter-level changes over time. The study showed ongoing subsidence in places that had high rates of groundwater extraction.
Why heavy rain didn't fix it
Even heavy rains and above-average snowmelt in 2022 and early 2023 were not enough to halt the sinking. While precipitation temporarily raised groundwater levels in parts of the basin, subsidence continued and in some areas even accelerated, indicating that natural recharge is unlikely to keep pace with current pumping rates.
Impacts and management
Subsidence has practical consequences: wells can run dry, cracks and fissures can appear in the ground, and infrastructure (roads, pipelines, irrigation systems) can be damaged. In response, policymakers designated the Willcox Basin an Active Management Area (AMA) in 2024 — a regulatory step that can limit groundwater extraction and help preserve remaining storage. Details of the basin’s management plan are still being developed.
Conway noted that similar policies have helped reduce subsidence elsewhere in Arizona: "Especially in the Phoenix and Tucson areas, groundwater levels are recovering, and we've seen subsidence rates decrease quite a bit. In the Tucson area, we're not even seeing subsidence anymore with the groundwater management."
Danielle Smilovsky of the Conrad Blucher Institute at Texas A&M University–Corpus Christi, lead author of the new analysis, offered a cautious outlook: "I don't think subsidence will ever stop," she said. "But an AMA might slow it down a bit."
Takeaway
Willcox Basin’s rapid subsidence underscores how intensive groundwater withdrawal can permanently reduce aquifer storage and create long-term risks for water supplies and infrastructure. Monitoring with satellites like InSAR provides critical, high-resolution evidence that can inform management decisions aimed at slowing — if not fully reversing — land-surface decline.