Intensity, Duration, and Frequency of maximum rainfall in Chile using high-resolution gridded precipitation products

Intensity-Duration-Frequency (IDF) curves are essential for urban drainage design, particularly during extreme precipitation events. Recent extreme hydro-meteorological events in Chile have caused important damages to society, ecosystems and infrastructure, revealing our societal vulnerability to such events. This work contributes to improve our understanding of the spatio-temporal distribution of maximum rainfall intensities for different durations and return periods in Chile. This study used three gridded precipitation products: IMERG (0.1x0.1), ERA5 (0.25x0.25), and ERA5-Land (0.1x0.1), and 175 hourly precipitation stations were used to compare maximum rainfall intensities from gridded P products. Annual maximum intensities (Imax) were estimated using a stationary and non-stationary Gumbel distribution, and then bias-corrected. Finally, Mann-Kendall test was applied to Imax for computing trends. The results showed that the spatial distribution of Imax shows higher values in Central-Southern Chile (30-46ºS), with Imax increasing in mountainous areas. The biases in Imax are low for durations longer than 12 hrs. For durations shorter than 12 hrs, IMERG overestimates Imax, while ERA5 and ERA5-Land underestimate it. Based on the Mann-Kendall test, the ERA5 and ERA5-Land exhibit a moderate decreasing trend in Imax in the Central Chile, while in the rest of the study area isolated trends are observed. Lastly, Both stationary and non-stationary IDF curves present small differences, generally less than 5 mm/hr