Analysis of historical and projected extreme precipitation in Buenos Aires city, Argentina.

Buenos Aires city, the capital of Argentina, lies on a plain covering 202 square kilometers, with a population of approximately 3 million. Together with the Metropolitan Area the population rises to over 14 million people, which makes it one of the most populated cities in the world. Buenos Aires is heavily vulnerable to climate change as it is increasingly affected by extreme precipitation, inland floods and more frequent storms.

This study examines extreme precipitation in Buenos Aires, focusing on trends in precipitation intensity and daily maximum rainfall during a historical period (1965–2014) as well as considering future projections (2015–2100) at the urban scale. Data from a meteorological station were analyzed for the historical period, while future projections were obtained using CMIP6 models, which were then downscaled and bias-corrected based on various Shared Socioeconomic Pathways (SSPs), including SSP1-2.6, SSP2-4.5, and SSP5-8.5. Both observed and projected data were also used to construct Intensity-Duration-Frequency curves, which are essential tools for designing urban infrastructure, drainage systems, and land-use planning.

Historical data shows that precipitation events have intensified in recent decades. Precipitation intensity has increased at a rate of 0.3 mm/decade, while the annual maximum daily precipitation has shown a rising trend of 2 mm/decade. Future projections under the most pessimistic scenario SSP5-8.5 indicate that the average intensity of precipitation events is projected to increase by 0.3 mm/decade, while the annual maximum precipitation rises by approximately 3 mm/decade. Conversely, under the most optimistic scenario SSP1-2.6, the average intensity shows non-significant changes while the annual maximum decreases by 0.5 mm/decade.

These findings suggest that precipitation events have become more intense in recent decades. Moreover, projections indicate that under the most pessimistic scenario, this trend of increasing intensity will likely persist or even worsen. This underscores the urgent need to implement climate adaptation strategies.