A comparison of recharge rates in aquifers of the United States based on groundwater-age data

Hydrogeology Journal
By: , and 



An overview is presented of existing groundwater-age data and their implications for assessing rates and timescales of recharge in selected unconfined aquifer systems of the United States. Apparent age distributions in aquifers determined from chlorofluorocarbon, sulfur hexafluoride, tritium/helium-3, and radiocarbon measurements from 565 wells in 45 networks were used to calculate groundwater recharge rates. Timescales of recharge were defined by 1,873 distributed tritium measurements and 102 radiocarbon measurements from 27 well networks. Recharge rates ranged from < 10 to 1,200 mm/yr in selected aquifers on the basis of measured vertical age distributions and assuming exponential age gradients. On a regional basis, recharge rates based on tracers of young groundwater exhibited a significant inverse correlation with mean annual air temperature and a significant positive correlation with mean annual precipitation. Comparison of recharge derived from groundwater ages with recharge derived from stream base-flow evaluation showed similar overall patterns but substantial local differences. Results from this compilation demonstrate that age-based recharge estimates can provide useful insights into spatial and temporal variability in recharge at a national scale and factors controlling that variability. Local age-based recharge estimates provide empirical data and process information that are needed for testing and improving more spatially complete model-based methods.

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Publication type Article
Publication Subtype Journal Article
Title A comparison of recharge rates in aquifers of the United States based on groundwater-age data
Series title Hydrogeology Journal
DOI 10.1007/s10040-011-0722-5
Volume 19
Issue 4
Year Published 2011
Language English
Publisher Springer
Contributing office(s) Toxic Substances Hydrology Program, Water Resources National Research Program
Description 22 p.
First page 779
Last page 800
Country United States
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