Hello François and It's brutal,
Several factors help explain the terrible number of victims and the violence of these floods, according to several experts.
According to the Spanish meteorological agency (Aemet), the equivalent of « d’a year of precipitation »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 – was such that it caused several rivers to burst from their beds and caused 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 affected areasSpain having experienced intense droughts over the past two years. This encouraged a phenomenon of runoff, with the earth proving incapable of absorbing all this water. Furthermore, the Valencia region, the most affected by flooding, is characterized by numerous artificialized areas, where natural spaces have given way to concrete, which is completely impermeable. There was “uncontrolled urbanization poorly adapted to the natural characteristics of the territory” in recent years, which today “amplifies” the risks, underlines Pablo Aznar, researcher at the Socio-economic Observatory of Floods and Drought (OBSIS).
Also, precipitation fell on heavily 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 “is a very important factor” to explain the impact of these floods, underlines Pablo Aznar, for whom the preparation of cities for climatic disasters constitutes a ” challenge “ for the authorities.
An aggravating factor also played a role in the terrible toll of these bad weather: the time at which they occurred. The bulk of the rain fell at the end of the day, at a time when many residents were on the road. According to the authorities, many victims died in their cars, surprised by the rising waters while they were returning home, or in the street, after trying to climb trees or lampposts. This situation could have been avoided if these people had been warned in time to allow them to return home earlier, according to Hannah Cloke, professor of hydrology at the University of Reading (United Kingdom). Aemet had issued on Tuesday morning a “red alert” for the Valencia region, calling for a “great caution” in the face of danger ” extreme “. But the Civil Protection service only sent its telephone alert message after 8 p.m. inviting residents not to leave their homes. THE lack of caution of some residents is also blamed: several admitted to having gone out despite the alert, explaining that they were not aware of the seriousness of the situation, citing too frequent alerts. “There were failures in communication”but there is undoubtedly 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 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 for the general population, so that they know how to act in the event of an immediate risk. »
