Hello François and it’s brutal.
Several factors help explain the terrible toll and violence of these floods, according to several experts.
According to the Spanish Meteorological Agency (Aemet), the equivalent of “ofa year of rainfall »in just a few hours. In Chiva, west of Valencia, the agency recorded no less than 491 liters of rain per square meter (49.1 cm). This flood – linked to a “cold drop” phenomenon, an isolated depression at altitude that is quite common at this time of year – It was such that it caused several rivers to overflow and the sudden formation of enormous torrents of mud. a cocktail “dramatic”according to Jorge Olcina, professor of climatology at the University of Alicante, who links this event to “global warming”. When they reach such magnitude, the “cold drops” can have effects “very similar” to those of a ” hurricane “insists this researcher.
The violence of the floods can also be explained by the Presence of dry soils in the affected areas.Spain has experienced intense droughts in the last two years. This favored a runoff phenomenon, in which the earth was unable to absorb all this water. Furthermore, the Valencian Community, the most affected by the floods, is characterized by numerous artificialized areas, where natural spaces have given way to concrete, which is completely waterproof. There was “uncontrolled urbanization and poorly adapted to the natural characteristics of the territory” in recent years, which today “amplifies” the risks, emphasizes Pablo Aznar, researcher at the Socioeconomic Observatory of Floods and Droughts (OBSIS).
In addition, rainfall fell densely populated areas and therefore mechanically affected a large number of people. The Valencia metropolitan area, where the vast majority of deaths occurred, has 1.87 million inhabitants. It is the third largest city in Spain. Urban density “It is a very important factor” explain the impact of these floods, emphasizes Pablo Aznar, for whom the preparation of cities for climate catastrophes constitutes an ” challenge “ for the authorities.
The terrible number of victims of these inclement weather conditions was also influenced by an aggravating factor: the time at which they occurred. Most of the rain fell late in the day, at a time when many residents were on the road. According to authorities, many victims died in their cars, surprised by rising water while returning to their homes, or in the street, after trying to climb trees or streetlights. This situation could have been avoided if these people had been notified in time to allow them to return home sooner, according to Hannah Cloke, professor of hydrology at the University of Reading (United Kingdom). The Aemet had issued on Tuesday morning a “red alert” for the region of Valencia, asking for a “great caution” in the face of danger ” extreme “. But the Civil Protection service did not send its telephone alert message until after 8:00 p.m., inviting residents not to leave their homes. HE Lack of caution by some residents. He is also blamed: several admitted to having gone out despite the alert, explaining that they were not aware of the seriousness of the situation and citing too frequent alerts. “There were communication failures”but there is certainly a “shared responsibility”estimates Pablo Aznar, who points out a problem in the “risk culture” Spanish. “The collective mentality is not yet sufficiently adapted to the new extreme phenomena”he insists. An analysis shared by Jorge Olcina, from the University of Alicante: “We will have to do much more to improve risk education in schools, but also among the general population, so that they know how to act in the event of an immediate risk. »
