Megadrought and intense rain: how to anticipate floods

March 22 is World Water Day. One challenge for society is understanding and anticipating how water behaves in an increasingly variable climate.

Over the past decade, Chile has faced a long water crisis, the so-called megadrought, and also more extreme hydrometeorological events. Recent reports by the Intergovernmental Panel on Climate Change project an increase in the frequency and intensity of extreme precipitation in south-central South America, even in scenarios where mean annual precipitation could decrease.

This situation calls for a better understanding of how the hydrological processes that control water in river basins are changing and, at the same time, for strengthening the country's ability to anticipate these events. That means improving the monitoring of hydrometeorological variables, extending the coverage of observation networks and developing tools that turn data into useful information for decision making.

During the rainfall event of January 31 in the Santiago Metropolitan Region, very intense rain fell on the western side of Santiago, particularly in municipalities such as Maipú, where flooded homes and waterlogged streets were reported. The Rinconada weather station in that municipality recorded about 17 millimeters of rain in less than an hour, enough to cause urban flooding in a short time. Other parts of the city received much less rain. Rainfall intensity can vary over very short distances, which makes these events hard to capture when monitoring networks are sparse.

Anticipating situations like this requires combining atmospheric and hydrological information. Hydrological models, real-time monitoring systems and forecasting tools help improve that ability.

At Universidad Técnica Federico Santa María, our Hydrology Group works in this direction. We analyze hydrometeorological data and model hydrological processes to understand how river basins evolve and how extreme events drive floods, and we develop forecasting tools to reduce their impacts. These topics will also be on the agenda of the upcoming Latin American Hydraulics Congress, to be held this year in Valparaíso, which will bring together researchers, professionals and students from several countries to discuss advances and solutions to Latin America's water challenges.