Academic Commons

Articles

Megacity pumping and preferential flow threaten groundwater quality

Khan, Mahfuzur R.; Koneshloo, Mohammad; Knappett, Peter; Ahmed, Kazi Matin; Bostick, Benjamin C.; Mailloux, Brian Justin; Mozumder, Rajib Hassan; Zahid, Anwar; Harvey, Charles F.; van Geen, Alexander; Michael, Holly A.

Many of the world’s megacities depend on groundwater from geologically complex aquifers that are over-exploited and threatened by contamination. Here, using the example of Dhaka, Bangladesh, we illustrate how interactions between aquifer heterogeneity and groundwater exploitation jeopardize groundwater resources regionally. Groundwater pumping in Dhaka has caused large-scale drawdown that extends into outlying areas where arsenic-contaminated shallow groundwater is pervasive and has potential to migrate downward. We evaluate the vulnerability of deep, low-arsenic groundwater with groundwater models that incorporate geostatistical simulations of aquifer heterogeneity. Simulations show that preferential flow through stratigraphy typical of fluvio-deltaic aquifers could contaminate deep (>150 m) groundwater within a decade, nearly a century faster than predicted through homogeneous models calibrated to the same data. The most critical fast flowpaths cannot be predicted by simplified models or identified by standard measurements. Such complex vulnerability beyond city limits could become a limiting factor for megacity groundwater supplies in aquifers worldwide.

Geographic Areas

Files

More Information

Published In
Nature Communications
Publisher DOI
https://doi.org/10.1038/ncomms12833
Volume
7
Academic Units
Lamont-Doherty Earth Observatory
Environmental Science (Barnard College)
Academic Commons provides global access to research and scholarship produced at Columbia University, Barnard College, Teachers College, Union Theological Seminary and Jewish Theological Seminary. Academic Commons is managed by the Columbia University Libraries.