On the attribution of changes in streamflow conditions to climate variability in North Carolina Piedmont, United States

Changes in streamflow magnitudes have ecological, hydrological, and geomorphological implications. Improved knowledge and understanding of the drivers of changes in streamflow conditions remain critical in water resource management. Spatiotemporal patterns of changes in streamflow conditions for five flow percentiles between two comparative periods: historical period (1944-1980) and recent period (1984-2022) were determined in 18 watersheds of North Carolina Piedmont. The observed percentage changes in streamflow magnitudes for the five flow percentiles were attributed to change magnitudes in monthly mean precipitation and monthly mean temperature using a statistical modeling framework (i.e. gamma regression model). The results showed reduced streamflow magnitudes for the 10th, 25th, 50th, and 75th percentile flows, respectively, while an increased streamflow magnitude was found for the 90th percentile flow at many of the sites in recent period. The regression models captured the relationships between change magnitudes in streamflow conditions and changes in climate variables across all the sites.