Decoupling Groundwater Trends From Climatic Drivers: Evidence of Human‐Dominated Aquifer Dynamics in a Mediterranean Island

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ABSTRACT Groundwater is the primary freshwater resource in Mediterranean islands, where limited surface water availability, irregular precipitation, and high evapotranspiration constrain hydrological resilience. Aquifers sustain urban, agricultural, and touristic demands during dry periods, yet projected warming threatens recharge. These pressures are further intensified by growing groundwater abstractions, including unregulated withdrawals, highlighting the need to distinguish climatic and human controls on aquifer dynamics. This study analyses long‐term groundwater evolution (1984–2020) in four groundwater bodies of Menorca using piezometric records from 18 monitoring wells. PCA identifies three dominant spatiotemporal patterns: (i) Widespread declines in intensively exploited aquifers (RC1; 11 wells), (ii) recovery trends in western sectors (RC2; four wells), and (iii) stable to erratic behaviour elsewhere (RC3). Mann–Kendall tests reveal predominantly negative trends (τ < −0.40 in ten wells), despite neutral to positive gross water balance signals, indicating decoupling between climatic water availability and groundwater storage. Multi‐scale correlation analysis between SPEI and SGI, computed separately for recharge and discharge phases on the representative well of each PCA group, provides process‐level evidence of this decoupling. The RC1 representative well (ME0456) exhibits negative or absent correlations across all accumulation scales and both phases. This pattern reflects a complete disruption of climate–groundwater coupling. The RC2 representative well (ME0050) maintains significant positive correlations (r up to 0.72, p < 0.05) at medium to long accumulation scales (12–48 months) in both phases, indicating preserved climatic connectivity. The RC3 representative well (ME0280) shows only limited positive correlations at short scales. The steepest declines occur in densely exploited coastal areas where illegal withdrawals contribute substantially, while recovery in western sectors reflects reduced pumping linked to alternative water supplies. Overall, results demonstrate how sustained human pressure overrides climatic controls, emphasising the need for improved abstraction control and integrated water management to enhance aquifer resilience in Mediterranean islands.

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