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Evaluation of the sustainability of deep groundwater as an arsenic-safe resource in the Bengal Basin

December 31, 2008

Tens of millions of people in the Bengal Basin region of Bangladesh and India drink groundwater containing unsafe concentrations of arsenic. This high-arsenic groundwater is produced from shallow (<100 m) depths by domestic and irrigation wells in the Bengal Basin aquifer system. The government of Bangladesh has begun to install wells to depths of >150 m where groundwater arsenic concentrations are nearly uniformly low, and many more wells are needed, however, the sustainability of deep, arsenic-safe groundwater has not been previously assessed. Deeper pumping could induce downward migration of dissolved arsenic, permanently destroying the deep resource. Here, it is shown, through quantitative, large-scale hydrogeologic analysis and simulation of the entire basin, that the deeper part of the aquifer system may provide a sustainable source of arsenic-safe water if its utilization is limited to domestic supply. Simulations provide two explanations for this result: deep domestic pumping only slightly perturbs the deep groundwater flow system, and substantial shallow pumping for irrigation forms a hydraulic barrier that protects deeper resources from shallow arsenic sources. Additional analysis indicates that this simple management approach could provide arsenic-safe drinking water to >90% of the arsenic-impacted region over a 1,000-year timescale. This insight may assist water-resources managers in alleviating one of the world's largest groundwater contamination problems.

Citation Information

Publication Year 2008
Title Evaluation of the sustainability of deep groundwater as an arsenic-safe resource in the Bengal Basin
DOI 10.1073/pnas.0710477105
Authors Holly A. Michaela, Clifford I. Voss
Publication Type Article
Publication Subtype Journal Article
Series Title Proceedings of the National Academy of Sciences of the United States of America
Index ID 70187196
Record Source USGS Publications Warehouse
USGS Organization National Research Program - Eastern Branch

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