Spatiotemporal Variability and Changing Seasonality of Extreme Flow Events in the Kentucky River Basin

ABSTRACT Understanding long‐term patterns in streamflow extremes is essential for watershed planning, especially under evolving climate conditions. While previous studies have reported changes in streamflow regimes, results have varied regarding the direction and timing of seasonal high and low flow events. This study examines daily discharge and seasonal climate data across four tributary watersheds in the Kentucky River Basin to characterize trends and variability in extreme streamflow conditions. Using percentile‐based thresholds, along with trend and autocorrelation analyses, we assessed changes in the timing, duration, and seasonal frequency of extreme high‐ and low‐flow events in the context of climate change and variability. Results show an increasing frequency of high vs. low flow events, particularly during spring and summer, concurrent with observed increases in seasonal precipitation and temperatures. The onset timing of main high and low flow event periods has also shifted further apart across the year. Autocorrelation analyses reveal multi‐year cycles in both streamflow and climate variables, suggesting that hydrologic extremes may reflect underlying long‐term variability. The nature and strength of these patterns vary across watersheds, potentially influenced by differences in watershed size, topography, and land cover. These findings underscore the need to consider both long‐term variability and watershed‐specific characteristics in watershed management strategies.