Spain remains dismayed by the innumerable damage that the eastern part of the peninsula has suffered this week due to DANA. The testimonies follow one another and the images on networks even remember the flood of the year 57 and the subsequent diversion of the Turia channel, a work that “has avoided a greater evil in the capital.”
In the balance sheets these days there is a lot of talk about causes, but also about prevention, because it is not the same as having a lot of rain or torrential rain, on Tuesday more than 500 liters per m² were recorded in about 4-6 hours, until they occur. floods and so many human losses to be regretted. From Carlemany University, geologist and professor Joan Escuer believes that phenomena may be natural but disasters are social. «During the last decades, specialists have made efforts to explain that disasters caused by natural events are not natural phenomena, but social ones, and that exposure and vulnerability to danger are the main factors that determine the very high levels of risk. “The representatives of the states that signed the Sendai Framework Agreement for Disaster Risk Reduction 2015-2030 agreed that risk reduction should be the main focus in disaster mitigation and prevention.”
And already in 2019, the Sustainability Observatory in collaboration with the General Council of the Associations of Insurance Mediators launched a study in which they affirm that almost one million people in Spain live in coastal areas with risk of recurring flooding. «Damage caused by natural disasters has increased by 900% since 1980 worldwide. In Spain, the impact of this damage has increased almost 200% since 1985. And floods are precisely the natural catastrophe that generates the most damage: 800 million euros per year,” La Razón recalled at the time.
Scientists explain in the media more and more often the existence and operation of phenomena such as rain bombs, that raining all at once, which is technically defined as a burst or “convective current that implies a collapse of heat transfer that is generated within a storm cloud. The pump carries with it most of the water content, it involves a “sudden” descent and occurs at a high speed (we are talking about 100-200 km/h. The impact on the ground is tremendous and, in addition, it causes radial winds that “They can exceed 150 km/h,” says the eltiempo.es website.
Jet stream, jet stream, Atlantic current or atmospheric rivers. The media pages are also increasingly filled with concepts that have to do with what is happening in an increasingly hot and unstable atmosphere. This fall alone saw a typhoon in Southeast Asia, torrential rains in central Africa with catastrophic results, and more rain-induced flooding in central Europe. Recurrent manifestations, scientists say, related to climate change. Added to this are constant announcements of record temperatures and emissions, which are as insistent in recent years as the heavy rains. Spain is in zone zero of impact from climate change and needs mitigation plans, says science.
hottest mediterranean
DANAS or cold drops are formed when warm, humid air evaporated from the sea encounters cold air at altitude. In the case of Valencia, a train of chained storms caused rains like they have not been seen in years. «The situation we have experienced combines the static location of DANA, the contribution of humidity from the Mediterranean with the easterly wind and the still warm waters of the sea. All of this combined with the orography and the planning of the territory results in the dramatic situation that we have experienced. DANA had the potential for very severe weather. Its location, its depth and the contribution of a high content of precipitable water favor the high potential for intense rains. In the case of Valencia, the establishment of a constant east flow affected the mountains near the coast, providing constant energy for the development of storms. While this situation remained stable for more than 12 hours, the storm cores developed constantly in the same area,” explains Mar Gómez, doctor in Physics and head of the meteorology area at eltiempo.es.
The physicist also recalls that “the continuous increase in temperatures in the Mediterranean poses a worrying scenario in terms of the intensity of extreme weather phenomena, especially DANAS. As this sea warms, it becomes a reservoir of energy and humidity that favors the formation of more intense storms with greater destructive capacity. The Mediterranean is an enclave where the combination of warm waters, air masses at high levels and complex orography on the surrounding coasts converge, creating an ideal breeding ground for meteorological phenomena to amplify,” says Gómez.
The Mediterranean is warming 20% faster than the world average and has risen 1.6 degrees in 40 years and the hotter it is, the more air vapor circulates over it. A fuel conducive to making the rains more intense. However, not only the Mediterranean coast is threatened by increasingly studied phenomena, but also the Atlantic. One of the latest climate alerts has to do precisely with this. Atmospheric rivers will be increasingly abundant and will affect the Peninsula more, in this case the Atlantic strip. These long, narrow bands, several thousand kilometers long, transport large amounts of water in the form of steam. When they reach the continental zone, they can condense and be released in the form of abundant precipitation. «Atmospheric rivers are responsible for almost 90% of the southern transport of moisture flow. In addition, they also contribute to the transport of latent heat between tropical latitudes and higher latitudes. These areas serve as highways that distribute humidity from tropical or subtropical areas to the middle and high latitudes of the planet,” says Gómez.
Adapt
These days there is talk about the need to prepare to face episodes of this type by changing urban planning or rather adapting it to climate change. Also, more generally, scientists are asking to stop reacting to extreme phenomena and start preventing and adapting by rethinking urbanization on the coast and river banks to leave room for water in the event of possible floods. A few weeks ago, when the arrival of Cyclone Boris in central Europe was announced, an unusual cold and very intense storm that was said to bring torrential rains and with the possibility of rain in mountain areas in the Alps, thousands of people were evacuated in the cities of Krnov (Czech Republic), which was almost completely flooded, and Cesky Tesin. “The Oder River, which flows into Poland, reached extreme levels in the city of Ostrava and Bohumin, prompting evacuations,” Euronews recalls. While this was happening in central Europe, accusations were made here about the lack of clear warning to the population.