Garda Flood Risk Management Urgently Needs Regional Coordination

“Tomorrow (for readers today) we will meet in Verona, in the Province, to find homogeneous solutions – explains Gardone Riviera’s mayor, Alessandro Bazzani, an engineer. – The water level of Lake Garda remains steady at 173 centimeters. The Sarca River adds 140 cubic meters per second, to which must be added the flow from torrents like the Barbarano, which is unmeasurable. In Peschiera, 190 cubic meters are discharged into the Mincio. The level should start to recede.

Unfortunately, if the wind picks up and the lagheggiata occurs, it would spell trouble for our lakefront. We have already rebuilt it twice in recent years.” Bazzani and the other mayors are furious about what happened in recent days, with the opening of the Adige-Garda tunnel, which for a few hours discharged 50 cubic meters per second, and later 100.

Emergency management and sudden decisions

“The head of civil protection in Trento – continues the engineer – decided to open the spillway without informing either the Magistrato del Po or the Magistrato di Venezia. He did it on his own initiative (fearing that Verona might flood). Then he commented: it was an emergency, after all, the lake level only rose by 17 millimeters.”

“We do not appreciate Trentino and Venetian authorities dumping their problems on Garda without informing those responsible. And that, in summer, Mantuan authorities use the basin for irrigation of the fields.” And the meeting we mentioned at the start? It is shaping up as a confrontation between regional and provincial authorities from Veneto on one side, and the Magistrato alle Acque on the other.

It has been organized by the provincial councilor for Ecology in Verona, Camillo Pilati, who has invited Garda authorities and bodies to a summit scheduled for 3 p.m. in Verona.

Local situation and infrastructure maintenance

The mayor of Gardone Riviera also informed the municipal council about the 45 bis issue and the need to identify an alternative route. “The landslide in Limone, then the one between Toscolano Maderno and Bogliaco. We thank Padreterno that there were no casualties. With provincial assessor Mauro Parolini, we will evaluate what to do.”

But let’s go back to levels. Alessandro Muraca, professor of Hydraulic Constructions at the University of Brescia and a consultant for some municipalities, has already explained that the Mori-Torbole tunnel can channel up to 500 cubic meters per second, and that “the water from the Adige, which is much colder and more polluted, carries substantial solid material.”

When it deposits into Garda, it forms a muddy zone facing the lakeside villages. In recent years, the focus has been on maintaining a high lake level during winter, risking some flooding, but avoiding dry summers. The maximum is usually reached in late spring, around May, when the level is about 140 centimeters.

“A compromise has been made: risk something in winter to ensure calm July and August periods. A solution might come from a rationalization of irrigation water use. By reducing summer withdrawals for agriculture, we could increase winter outflow.”

Flooding issues and water management

And what about the continuous flooding? “The greenery continues to diminish. Every time construction occurs, with the same amount of rainfall, the amount of stormwater runoff increases. Water no longer penetrates the ground. It ends up in rivers, ditches, and the lake.”

“In some European countries, to promote drainage, construction companies are required to create permeable pavements or reservoirs that collect water in containers, to be drained into the ground once the emergency is over. But all this has a cost, borne by builders, which is still lower than the cost to society in case of floods,”

Guido Maruelli, president of the special company Consorzio Garda Uno, states that “the situation is serious. We are engaged daily in systematic checks of the entire sewer network and the collector. In short, minute-by-minute monitoring.”

Authorities’ interventions and responsibilities

Meanwhile, the Lega councilor from Desenzano, Rino Polloni, wrote to the President of the Republic, Ciampi, emphasizing the unedifying game of ping-pong among authorities in the recent incident of Garda’s (non)flooding, and asking who is responsible for regulating the Adige drainage tunnel.”