Multi-decadal groundwater observations reveal surprisingly stable levels in southwestern Europe

Abstract

Abstract Climate change and human activity are leading to water scarcity in southwestern Europe. Groundwater use is thought to be unsustainable in the region, yet regional assessments using measured data are missing. Here, we evaluate long-term trends and drivers of groundwater levels and found a more complex situation. Historical data (1960–2020) from 12,398 wells in Portugal, Spain, France, and Italy showed 20% with rising groundwater levels, 68% were stable, and only 12% were declining. Rising wells in temperate climates were due to increased precipitation. Recovering wells in semi-arid regions were attributed to improved groundwater management. Stable wells are concentrated in temperate climates with year-round high precipitation. Declining wells in semi-arid regions are primarily located near agricultural areas and experience prolonged summer soil moisture loss, whereas in temperate regions, the decline is associated with large urban areas. Systematic groundwater monitoring and data sharing are essential for sustainable and science-based water resources management.