Trends in surface water and groundwater 1980-2020 for the lower 48 United States

Trend classifications in surface water (left) and groundwater (middle) from 1980 to 2020 by Hydrologic Landscape Regions (top) for the lower 48 United States. Darker colors indicate more likely trends and lighter colors indicate less likely trends, with red indicating drying trends and blue indicating wetting trends. Agreement in trend classifications (right) between surface water and groundwater, where dark blue indicates agreement in likely wetting from 1980 to 2020 and dark red indicates agreement in likely drying trends. Grey areas indicate agreement that no trend is likely, orange indicates areas with significance mismatches, and purple indicates areas with trend direction mismatches. 

Figures extracted from Johnson and Walvoord, 2026. DOI: 10.1088/3033-4942/ae89dd