Variations of, and Changes in the Hydroclimatology of the Southeast United States

Abstract:

The hydroclimatology of the southeast United States (AL, GA, NC, SC and TN) is analyzed from a holistic perspective, including multiple climate drivers that have been investigated separately in previous research. Monthly precipitation modelled by the PRISM group, and runoff data (1952-2011) from 18 unregulated basins (USGS) are analyzed using a single-field based Principal Component’s Analysis. Results indicate that the Atlantic Multidecadal Oscillation and El Nino-Southern Oscillation are the main drivers of hydroclimate variability in the region, sometimes operating at several months lag. Their influence is the strongest in the fall through spring, which corresponds with the dry season in the southern parts of the study area, increasing pressure on already limited water resources. The North Atlantic Oscillation and Pacific-North American patterns vary on shorter term bases, and also show a significant, but temporally more sporadic influence. A study of the relationship between the time series of precipitation and runoff indicates that the correlation between the two has become stronger over time, particularly in winter and spring, indicating an altered hydrologic cycle, which might be explained by a warmer climate.

Findings can be used in water resources forecasting, indicating expected water volumes several months ahead and giving an idea about future changes to the water cycle, following a warmer climate.