Construction and Application of Intensity‐Duration‐Area‐Frequency Curves at Seasonal and Annual Precipitation in Yangtze River Basin

ABSTRACT Extreme precipitation aggregated in time and space will lead to the superposition and amplification of disaster risks, causing significant impacts on social economy and ecological environment. Incorporating the area factor into the extreme precipitation risk assessment framework using intensity‐duration‐area‐frequency (IDAF) curves can effectively evaluate the superposition and amplification effects of extreme precipitation events. Therefore, this study utilised high spatiotemporal resolution precipitation data (i.e., 0.1° × 0.1° and 3 h) from the Yangtze River basin (YRB) in the period of 1979 to 2020 to establish seasonal and annual IDAF curves at multiple spatiotemporal scales (i.e., 3–96 h and 144–961 km 2 ) for the first time in the YRB. The extreme precipitation intensity at different spatiotemporal scales and return periods was estimated, and the patterns of its variation with spatiotemporal scales were also investigated. The results indicated that: (1) The goodness‐of‐fit of the Extended Generalised Pareto Distribution –IDAF (EGPD‐IDAF) model exhibited significant seasonality and scale dependency, with the best fitting effect in summer and at the mesoscale (i.e., 24 h and 144 km 2 ); (2) At the 3–6 h scale, extreme precipitation return levels in the YRB exhibited higher sensitivity to variations in area, showing greater fluctuations, whereas as the temporal scale increased, the impact of area variation gradually weakened; (3) The maximum return levels of extreme precipitation in the eastern sub‐basins of the YRB occurred at the spatiotemporal scale of 3 h and 144 km 2 , representing local short‐duration heavy precipitation, while those in the inland sub‐basins occurred at the large scale of 961 km 2 with a temporal scale of 24 or 48 h. This study elucidates the area effect of extreme precipitation events in the YRB and establishes the relationship between extreme precipitation return levels and duration and area, offering significant value for regional climate services and disaster risk management.