“An event that marked history”. Even from a From a scientific point of view, the flood was a caesura: there is a before and an after. To take stock of what has changed, and above all what must change for an event like that of May last year to produce less damage, was the conference “Ravenna, one year after the flood” organized by the institutions, Flaminia Foundation and Unibo which brought together experts and professors from the University in remembering, informing and present scientific studies resulting from that tragic event.
On the causes but above all on theexceptionality of the event he intervened Marco Maraniof the Center for Studies on the Impacts of Climate Change of the University of Padua: “A lot is linked toApennines which played an important role in determining this intensity. An extreme event that has a minor precedent, like the flood of ’39 which however did not produce the same effects”. Extreme, but repeatable? “Was especially exceptional is the sequence of two very important events in one area. It was extraordinary and infrequent but it can happen again. An event with these characteristics in itself, it would have a multi-centennial frequency, from 200 to 500 yearsBut they play against us climate changes that we are now able to document and quantify. And they tell us that these events may become more frequent. So we have to prepare and get used to it.”
Matteo Berti, researcher and teacher of Applied Geology at the University of Bologna took stock of the landslide situation in the hills: “In our mapping we took a census 80 thousand landslide phenomenon, from Borgo Tossiranno to Modigliana. There are areas where there are more than 200 landslides per square kilometre and if we put it together the area of the landslides is 84 square km, more than the municipality of Modigliana. But they are not all the same, he specifies.
“Landslides are a bit like diseases, some are treatable, others are not. Most in Romagna are curable, with consolidation interventions. With landslide blanket protection, geomats or cortical reinforcements Most of these situations can be resolved. However, there are larger landslideslike that of via dei Laghi and via dei laghi in Modiglianaor the one along there provincial road south of Casola Valsenio, or even the one that caused one death, between Fontanelice and Casale. They are large rock landslides, dangerous and fast. It is difficult to consolidate them: the construction sites must be activated. For now, however, what has been done is temporary safety measures. The procedure for reconstruction is now well codified in the commissioner structure: we intervene first on the infrastructures, then on the landslides that have interrupted roads and then on all the others”.
And what effect can the bad weather, even violent ones, which are hitting our territory in “cells” have?
“Many landslides have left the slopes injured, without vegetation and the ground exposed. We feared that this would produce erosion phenomena. But instead the slopes reacted well. The material that makes up Romagna is quite sandy and of good quality and is less subject to reactivation. This gives us a little more time to fix the hill.”
