A Bayesian framework for uncertainty quantification of rainfall Intensity–Duration–Frequency (IDF) curves

Extreme climate events are projected to occur more frequently in the southeastern United States. However, uncertainties associated with climate studies, particularly those concerning extreme rainfall events, are often neglected due to limitations in climate models, insufficient data, and incomplete understanding of underlying physical processes. This study aims to update and quantify the uncertainties associated with future projected rainfall Intensity-Duration-Frequency (IDF) curves using Bayesian framework under the RCP8.5 scenario. Results indicate that IDF curves developed for the historical baseline (1974–2013) showed lower rainfall intensities compared to NOAA Atlas 14, with differences ranging from −20% to −2%. Comparisons between the Ensemble RCM projections (2030–2059) and the historical baseline revealed that shorter durations showed smaller changes, whereas longer durations exhibited substantial increases in rainfall intensity, indicating significant projected impacts of climate change on extreme rainfall events. The relative changes in rainfall intensities ranged from −43% to 220%. The uncertainty assessment showed rainfall intensity spreads ranging from 1 mm/h to 56 mm/h at the 95% credible interval. Mean rainfall intensities for durations of 0.25, 0.5, 1, 3, 6, 12, and 24 h across the 2-, 5-, 10-, 25-, 50-, and 100-year return periods ranged from 6 mm/h to 177 mm/h.