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@ARTICLE{2026JHyd..67135180H,
       author = {{Hodgkins}, Glenn A. and {Simeone}, Caelan E. and {Lombard}, Melissa A. and {Caldwell}, Todd G. and {Hammond}, John C. and {Wieczorek}, Michael E. and {Dudley}, Robert W.},
        title = "{Groundwater drought in the United States: spatial and temporal variability}",
      journal = {Journal of Hydrology},
     keywords = {Groundwater, Drought, United States, Variability, Wells, GRACE},
         year = 2026,
        month = may,
       volume = {671},
          eid = {135180},
        pages = {135180},
     abstract = "{Many communities and ecosystems in the United States that are dependent
        on groundwater are potentially adversely affected by groundwater
        drought. We computed yearly groundwater-drought metrics and mean
        groundwater levels at well locations across the conterminous
        United States (CONUS), using data from wells and remotely sensed
        and modeled Gravity Recovery and Climate Experiment Drought
        Monitor Data Assimilation (GRACE-DADM). We also modeled the
        probability of low or high human impact at each well location.
        The spatial distribution of groundwater-drought duration and
        severity from 2001 to 2020 for 1,510 wells shows longer maximum
        duration and higher maximum severity events in drier regions
        like the Southwest than in wetter regions like the Northeast.
        Based on 613 wells in CONUS from 1981 to 2020, there are many
        significant decreases in drought duration and severity in the
        Northeast and many significant increases in annual-mean
        groundwater levels. In contrast, there are many significant
        increases in drought metrics and decreases in mean water levels
        in parts of the Southeast. There are major differences in trends
        from 2001 to 2020 between well-based and GRACE-DADM-based
        groundwater metrics in some CONUS regions and a very low
        correlation between trends at individual locations across CONUS.
        A potential reason for this disparity is the low GRACE-DADM
        resolution ({\ensuremath{\sim}}12 km) and the potential for a
        large amount of groundwater variation at the local scale. Also,
        GRACE-DADM represents shallow, unconfined aquifers which may not
        match the screened interval of the monitoring wells we
        evaluated. Large spatial gaps in long-term, high frequency, and
        quality-assured groundwater-well monitoring data present a
        challenge for understanding groundwater-drought variability
        across CONUS. Remote sensing tools such as GRACE can help but
        cannot fully replace well monitoring, as highlighted by our
        study results. Substantially more long-term monitoring wells
        would more accurately represent groundwater-drought trends and
        spatial variability across CONUS, particularly in western
        regions.}",
          doi = {10.1016/j.jhydrol.2026.135180},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2026JHyd..67135180H},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}