The flood in Tuscany?An event that occurs once every 100 years.And the problem is that the soil no longer 'holds' water

The expert in hydraulic systems and naturalistic engineering Federico Preti explains how impressive the violence of the flood of November 2nd in Tuscany was.And because the territory today is much more fragile to 'withstand' such an event

FLORENCE – “The areas of Prato, Pistoia and Lucca are the most urbanised. The weather event this early November was impressive:flooding and flooding in urbanized areas, cumulative rainfall of up to 160 mm in 3 hours, rapid increases in hydrometric levels of up to 4-5 meters in watercourses, with response times similar to the duration of rainfall".Professor Federico Preti, professor of Agricultural Hydraulics and hydraulic-forestry arrangements at the University of Florence and national president of the Italian Association of Naturalistic Engineering (Aipin), explains it.

“It's true that we have more frequent intense and localized rainfall, suddenly switching from drought to floods - he continues - but what does the hydrogeological risk, which I would now call 'hydrogeobuilding', depend on?From the danger, what does it tell us how high is the possibility of this type of event occurring, or how many years can pass between it and another of equal or greater intensity, in the case in question we talked about return time of 50-100 years“.

READ ALSO: More and more extreme events in Italy:in 13 years almost 300 deaths
READ ALSO: Hail, fires, winds and heat:if big data helps us defend ourselves from extreme events

THE SOIL NO LONGER HOLDS WATER, TOO MANY HOUSES AND INFRASTRUCTURES

But it also depends "on the vulnerability and market value of assets exposed to the damage they may suffer - continues Preti - not to mention the infinite value of human lives. Today we have a territory that does not 'hold' water upstream, which arrives in large quantities and too quickly downstream, where now there are more homes and infrastructure than before.Today we had the expansion tanks which, fortunately, worked.But before we had widespread lamination in drains and aqueducts, terraces, reservoirs, etc.that are lost.From our studies, now also ascertained in international scientific literature, the volumes of water and the slowdown in flow times we had were completely similar to those we try to obtain with new works to be built along the waterways.And the increase in the forest does not compensate for the increase in waterproofing and the loss of regulation."

THE FLOOD IN FLORENCE 70 YEARS AGO, BUT NOW THE TERRITORY IS MORE FRAGILE

Now, explains the president of the Italian Association of Naturalistic Engineering, there are also about "ten stretches of embankments to be repaired, an essential operation, but let's remember that these only protect what they separate from the riverbed, encouraging further construction and transferring more water and more quickly downstream.Today 57 years have passed since the flood in Florence and, in the last 60-70 years, we have lost control and maintenance of the territory, now more fragile and vulnerable and we must start again from there“.

READ ALSO: Almost 94% of Italian municipalities are at risk of hydrogeological instability
READ ALSO: Climate change skepticism is rampant on Twitter

INTERVENTIONS INSPIRED BY NATURE ARE NEEDED

Certainly, then, it is necessary to "compensate and mitigate the increase in risk with so-called 'Nature Based Solutions'.The discovery of hot water?It's about interventions inspired by nature, or Naturalistic Engineering which is well known and tested in our country, as regards our hilly and mountain basins.In urban areas, some would be useful vegetated areas and strips that can slow down water flows before entering sewers or drainage networks.In addition to relocating structures at excessive risk."According to the expert, in fact, we can no longer exempt ourselves from the "maximum applicability of these interventions (naturalistic engineering instead of gray engineering, unless the limits are demonstrated) and we should implement the European directives on control of land consumption and on the use of environmentally friendly and sustainable materials and solutions,” he concludes.