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 I_max 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 I_max 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.