overpumping

Overpumping is the extraction of groundwater at a rate that exceeds natural recharge over an extended period. This can cause a decline in groundwater levels, known as drawdown, and may produce a cone of depression around pumping wells. When persistent, overpumping depletes aquifers, reduces storage, and can lead to land subsidence that damages infrastructure such as roads and buildings. It can also lower surface water flows and degrade water quality, for example through saltwater intrusion in coastal aquifers and changes in spring or river baseflow.

The primary drivers are irrigation for agriculture, municipal and industrial water supply, drought, and population growth, often compounded by inefficient irrigation practices and a lack of regulatory controls.

Hydrogeologists monitor overpumping through groundwater level measurements in observation wells and by using remote sensing methods to detect subsidence and changes in groundwater storage, such as satellite gravity data and InSAR analysis.

Mitigation and management aim to balance extraction with recharge and reduce demand. Approaches include managed aquifer recharge and artificial recharge, improvements in irrigation efficiency and conveyance, water pricing or allocation to prevent overdraft, pumping policies, and drought contingency planning. Restoring groundwater levels may require long-term changes in water use and land management, sometimes with crop switching or water recycling.

Global cases include substantial subsidence in parts of California’s Central Valley and Mexico City, where prolonged overdraft occurred. Many regions pursue integrated water resources management to prevent future overpumping and to sustain groundwater supplies.