The intensity of this cutoff low does not justify the severity of the tragedy

The cutoff low, popularly known as a cold drop, that began on 29 October was very intense and the consequences were severe. Many weather stations recorded rainfall of more than 200 mm in a few hours, and some exceeded 600 and 700 mm in a single day, higher than the annual total for most years (Figures 1 and 2). Records were broken for the amount of rainfall per hour (179 mm in Turís). As a consequence, rivers have burst their banks, houses and bridges built centuries ago have been destroyed, and large areas, some of them densely populated, have been flooded (Figure 3). Material damage is uncountable; initial estimates refer to 75,000 houses affected in 47 municipalities, and more than 3,000 km of streets and roads flooded. Public transport has been severely affected throughout the territory; we have had no suburban or long-distance trains for several days, and no metro in the city of Valencia and the metropolitan area; many roads have been cut off. Thousands of people have been unable to communicate at home for several days; the death toll exceeds 200 and many are still missing; we mournfully await an update on these figures. This is an unmitigated tragedy. Neither the floods of 1957 nor the breaking of the Tous Dam in 1982 were anywhere near as deadly.

It is not normal in a Western country for so many people to die in a storm of a kind that is not uncommon in our land. We have experienced many cold drops. What happened in this case? To answer this question, it is important to differentiate between the causes of this cutoff low (the intensity of the meteorological phenomenon) and the causes of the tragedy (the severity of the consequences). The consequences do not depend only on the intensity of the disturbance; the social context and political decisions also play an important role. In other words, the catastrophe that is being experienced in Valencia does not depend solely on the intensity of the event, but in particular on the prior prevention and the management during and after the storm.

Figure 1. Precipitation (mm) at Turís-Canyapar (Turís, Ribera Alta) on 29 October. The annual average (period 1991–2020) at this station is 475 mm. The alarm to the population was given after the rains (at 20 h), instead of before the rain started at 14:30 h. / Source: AVAMET and À Punt Media.

A particularly aggressive event

We have cutoff lows almost every year, but this one has certainly been particularly intense and aggressive. The sea has been at an unusually high temperature for several months, which leads to more evaporation and therefore to a larger accumulation of water vapour in the atmosphere. In addition, warmer air holds more water vapour than colder air, and we are having a particularly warm autumn. This larger water vapour load increases the likelihood of a sudden release of vapour and an extreme cutoff low. Consequently, climate change increases the frequency and intensity of these storms. In addition, the drying up of coastal wetlands and the replacement of natural ecosystems with concrete infrastructure increases the temperature and decreases the humidity of summer sea breezes, which reduces summer storms in the coastal mountains. This facilitates the accumulation of water vapour during the summer. All these factors condition the intensity of the weather event, but not the severity of its consequences.

Figure 2. Rainfall distribution map for the fateful Tuesday 29 October. Turís (Figure 1) is located between Chiva and the river Magro. Source: AEMET

A colossal tragedy

The consequences of a cutoff low, like any other disruption to social systems, depend on socio-economic and political factors. In and around Valencia, urban planning seems to be more oriented towards economic benefits than resilience to disturbances such as extreme storms and floods, even though these are not at all rare in our history. Construction is often carried out in close proximity to rivers, streams and ravines, leaving no open spaces with vegetation to buffer the floods; there are many constructions in declared flood zones; and transversal constructions (roads and motorways) that impede the passage of water are not uncommon. In addition, the lack of an official, forceful and timely warning to the population by the corresponding administration (in this case, the Generalitat Valenciana) has been particularly relevant in this catastrophe. Meteorologists had predicted a few days earlier that a particularly extreme cutoff low was approaching. On Monday 28th, the University of Valencia (which has its own emergency committee) decided to cancel all activities for Tuesday. On Tuesday morning, the 29th (the fateful day), both the AEMET and the Confederació Hidrogràfica del Xúquer warned of the danger of extreme storms and an alarming accumulation of water at the top of the basins. Apparently, the emergency manager of the Generalitat Valenciana ignored the warnings and did not issue an official alert until it was too late (at 8pm). When it was already raining heavily in the interior regions and the flows were increasing alarmingly, those living downstream, where it was hardly raining and where they were going about their normal lives, were not alerted. Many people were only warned when they were already trapped by the flooding. Schools should have been closed that day and work activities limited. Now we see the result of not listening to the specialists.

As so often, the limiting factor is not science or technology, but human decisions and information management. There is a lack of spatial planning with floods in mind, which is probably the most important risk in the Mediterranean area; the mapping of flood-prone areas has been available for a long time. The management during the fatal event was not correct, the civil prevention and warning system did not work. The management of the days that followed also leaves much to be desired; aid is taking a long time in many places and people feel helpless; the collaboration of different brigades offering help, both from the region and from outside (both national and international) was not accepted; the volunteers, who have given a lesson in solidarity, have felt cheated by the administration; some politicians have shown very little empathy with the victims; and there is suspicion that the figures for the number of victims are not being updated. The Valencian people are outraged.

Figure 3. Landsat-8 satellite image from 8 October (before the event, left) and 30 October (right). / Source: European Space Agency.

Will we learn the lesson?

We may not be able to avoid an event of these characteristics, but we can avoid a tragedy of these magnitude. Technically, we are prepared to prevent or at least reduce catastrophes of this scale; politically, it seems that we are not. Responsibility will have to be established and possible negligence will have to be traced. We will have to assess whether it was really a good idea to abolish the Valencian Emergency Coordination Unit. The state’s representatives in emergencies and civil protection failed; it is also important to be self-critical about our personal behaviour in the face of the available information. And the best thing we can do now is to learn from our mistakes, which is how societies mature. This tragedy must strengthen Valencian society and prepare it for the next cutoff lows, which are sure to come. The challenge is to ensure that the next one, even if it is more intense, has no consequences on the population, or as few as possible.

Among the actions that need to be improved, we could highlight the following: 1) Implement effective policies to reduce climate change; 2) Restore, as far as possible, wetlands and coastal vegetation, avoiding the expansion of urban and industrial areas on the coast, and increasing green areas and woodland in urban areas in and around Valencia; 3) Carry out planning maintaining and respecting natural drainage and flood zone mapping, and reducing population density in these areas; 4) Having a highly specialised and coordinated emergency unit, capable of generating localised warnings and with the capacity to react quickly, and as independent as possible from political power; 5) Informing people who live (or who want to buy property) in areas classified as flood prone about the risk they have to accept; educating the population to understand and react to the risks, including courses, workshops, and drills for people who live in flood prone areas.

All of this requires a willingness to change, to leave behind the dynamics of the 20th century and rise to the challenge of the 21st century. Are we ready?