Bad weather returns to plague Emilia-Romagna: after the red alert declared for Saturday in the Region, between Saturday 19 and Sunday 20 October 2024 storms and floods hit the entire Emilia and Romagna region, especially in the area of Bologna and some neighboring municipalities such as Pianoro, San Lazzaro di Savena and Casalecchio di Reno, where it peaks up to 175 mm rained in the space of a few hours (a quantity that at this time of year is expected in two months) broke the banks and caused numerous rivers and streams to overflow, causing extensive damage and unfortunately also one victim, the twenty-year-old Simone Farinellioverwhelmed by the car in Pianoro by the flood of the Zena torrent. In the province of Bologna alone they were 3500 people evacuated and bad weather knocked out electricity at least 15,000 buildings. Only yesterday they were 515 interventions by the Fire Brigade in the Region.
How much it rained in Emilia-Romagna: rainfall data
The extreme bad weather in Emilia was caused by the convergence along the Apennine side of sirocco currents coming from a disturbance in the Tyrrhenian Sea and bora currents coming from the north-east. The meeting between hot air and cold air created the conditions for the formation of intense precipitation. There Cumulative precipitation map drawn up by Arpa Emilia-Romagna shows that the maximum accumulations (violet colour) occurred around the Bologna area in correspondence with the Samoggia, Idice and Savena basins. They registered in Bologna San Luca 148.5 mm in 24 hourstouching the historical maximum of 150 millimeters dating back to 27 September 1928.
Here the rainfall also recorded values higher than 30 millimeters per hourwhich would be high even for a summer storm. With the difference that while summer storms are usually very short, this rapid accumulation lasted for several hoursliterally flooding land already saturated with water. In fact, let’s remember that in the Bolognese area it had already rained approximately 300 mm in Octobera quantity already higher than the average for the period; imagine what another 150-170 millimeters in 24 hours can mean in a soil already so full of water.
The result has been seen: waterways such as the Ravone, the Samoggia, the Ghironda, the Lavino and the Savena have exceeded historical highs which had been reached during the flood events of May 2023. The Ravonefor example, scored a level of 3.14 meters (the alarm is triggered above 2 metres), well above the historic maximum of 2.54 meters in May 2023.
Comparison with previous floods in Emilia-Romagna
Unfortunately, the last few days were the fourth flood event in Emilia-Romagna in less than a year and a halfafter the two floods of May 2023 and the one in September 2024 due to storm Boris. We know that Emilia-Romagna is a region particularly subject to this type of event, but four floods in a year and a half is a given exceptionalespecially considering that events of this severity should recur in the area in a minimum time of several decadesnot a few months.
Looking at the raw data, 19-20 October 2024 in Emilia-Romagna it rained less than in previous floods. The September 2024 flood was particularly serious due to the very high rainfall, with peaks of 350 mm in 24 hourswhile in May 2023, 400-450 millimeters were reached during two separate flood events. The events of May 2023, however, were characterized by high persistence, with a duration of even 36 consecutive hours.
In recent days there have therefore been fewer millimeters and fewer hours of rain, but this does not mean that it was a less serious episode. This is because we must consider the fact, already mentioned before, that the ground was already saturated with watertherefore less is needed to do the same damage. Furthermore, in general the Emilian territory was already widely tested by previous disasters.
A new climate normal?
In light of all this, it would be wrong to consider what happened as a series of isolated unfortunate events. What we are witnessing is the result of critical conditions which have been recurring for months in a meteorological context in which disturbances are increasingly frequent and more intense. Meanwhile, in Southern Italy there have been long and prolonged lockdowns in recent months drought with great difficulties in supplying water.
The two conditions are only apparently contradictory: in reality they fall within the framework expected in a context of global warming, which has among its effects the increase in extreme meteorological phenomena in one direction and the other. Substantially, the increase in average temperatures “accelerates” the water cycle, increasing the water vapor available in the atmosphere for precipitation and the energy that can be discharged from precipitation, thus creating the conditions for an increasingly accentuated alternation between short periods of extreme rainfall And long dry periods. The data tells us that this is also happening in Italy, where in 2023 extreme weather events increased by 20% compared to the previous year.
Among the population all this can create a habituation effect, of the type «But enough, every time it rains somewhere there is a red alert». This in turn leads to perceiving the state of red alert as something that has lost its meaning of urgency and emergency, something that can also be ignored, because we continually hear this term even when it is not raining in our area. But somewhere else embankments break, roads flood and in the worst cases even human lives are lost. The sensationalism of the Civil Protection or the media has not increased: the frequency of events that we once called “exceptional” has increased.
This forces us not only to rethink our infrastructure or hydrogeological risk management plans in Italy, but also to the fact that there is no need to blame this or that scapegoat from time to time for every single disaster, but to prepare ourselves for a new meteorological-climatic normality.
