Study Finds Humans, Not Climate, Main Driver of Arizona Groundwater Loss
Image: Jennifer McIntosh/Department of Hydrology and Atmospheric Sciences
A recent study led by researchers at the University of Arizona finds that human groundwater pumping has played a larger role than long-term climate variability in depleting groundwater in southern Arizona. Published in Water Resources Research, the study reconstructs groundwater levels in the Tucson Basin over approximately the past 20,000 years using chemical and isotopic tracer data from wells.
The results show that past climate shifts, such as prolonged dry periods, did lower groundwater levels, but these declines were modest compared to the dramatic drawdown caused by modern groundwater pumping since the mid-20th century. In fact, recent human-driven declines are estimated to be roughly twice as large as those caused by natural climate variability alone.
The study also highlights that natural recharge rates in the region are slow, meaning that even a return to wetter climatic conditions would be insufficient to fully recover groundwater lost to intensive extraction. These findings emphasize that water scarcity in Arizona is primarily a management, rather than a climate, challenge.
This research was supported in part by WRRA Section 104(b) funding, which helps advance applied water resources research and supports science-based decision-making for sustainable groundwater management in Arizona.