The imprint of climate and geology on the residence times of groundwater Public Deposited


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  • Surface and subsurface flow dynamics govern residence time or water age until discharge, which is a key metric of storage and water availability for human use and ecosystem function. Although observations in small catchments have shown a fractal distribution of ages, residence times are difficult to directly quantify or measure in large basins. Here we use a simulation of major watersheds across North America to compute distributions of residence times. This simulation results in peak ages from 1.5 to 10.5 years, in agreement with isotopic observations from bomb-derived radioisotopes, and a wide range of residence times—from 0.1 to 10,000 years. This simulation suggests that peak residence times are controlled by the mean hydraulic conductivity, a function of the prevailing geology. The shape of the residence time distribution is dependent on aridity, which in turn determines water table depth and the frequency of shorter flow paths. These model results underscore the need for additional studies to characterize water ages in larger systems.
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Date Issued
  • Maxwell, R. M., Condon, L. E., Kollet, S. J., Maher, K., Haggerty, R., & Forrester, M. M. (2016). The imprint of climate and geology on the residence times of groundwater. Geophysical Research Letters, 43(2), 701-708. doi:10.1002/2015GL066916
Journal Title
Journal Volume
  • 43
Journal Issue/Number
  • 2
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  • This work was supported by the National Science Foundation grants WSC-1204787 and DGE-1069333, and by the US Department of Energy Office of Science, Offices of Advanced Scientific Computing Research (ASCR) and Biological Environmental Sciences (BER).
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