The global groundwater research knowledge divide

Groundwater underpins global water security, supporting nearly half of irrigation and domestic water use. Yet the scientific knowledge base informing its management is unevenly generated and disseminated. Here, we use large-scale bibliometric analysis of 53,163 groundwater-related scholarly publications produced over the last ∼ 50 years, combining keyword co-occurrence mapping, document co-citation analysis, and collaboration network analysis to examine the evolution of research themes, geographic contributions, and international collaboration networks. We show that groundwater science has expanded exponentially, shifting from predominantly local hydrogeological characterisation toward sustainability, water quality, and climate-resilience research. However, this growth is highly concentrated, a small group of high-income countries accounts for 62% of publications and 68% of citations, while many groundwater-dependent regions remain marginal in both knowledge production and collaborative networks. These structural imbalances constrain the transfer of scientific insights to regions facing the greatest groundwater stress, risking maladaptive management and undermining progress towards Sustainable Development Goal 6, one of the 17 Sustainable Development Goals adopted by the United Nations . This study provides one of the most comprehensive global bibliometric assessments of groundwater research, quantifying thematic evolution, geographic inequities, and collaboration structures across the field. Our findings provide a quantitative foundation for rethinking how groundwater knowledge is generated and shared, highlighting the need for targeted capacity building, open data infrastructures, and more inclusive international research partnerships to support evidence-based groundwater management and accelerate progress toward SDG 6. Overall, the results highlight the urgency of prioritising equitable groundwater research investments to close the global groundwater knowledge divide