Centuries ago, the country began building artificial barriers and dams in many mountainous areas, which make up about 70 percent of Italian territory, but maintenance was gradually abandoned. The solution to flooding on lower-lying plains starts there, said Mauro Agnoletti, the UNESCO Chair on Agricultural Heritage at the University of Florence. Maintenance must be increased, he said, “especially in areas upstream of cities.”

Italians generally do not dwell on the fact that their livelihoods, or their lives, could be at risk from natural calamities — at least not until disaster strikes, experts say.

That indifference puts risk assessment, and risk prevention, “out of the political agenda,” said Erasmo D’Angelis, the former head of Safe Italy, a government organization, who evaluated such risks and allocated funds to offset them.

“Major, national public works project must immediately get on the way in order to ensure the safety of millions of citizens,” he said, “not to mention an enormous industrial and cultural heritage.”

To confront the challenges of climate change, some experts have suggested stopping land consumption and redeveloping or reclaiming abandoned, polluted or degraded areas. Where new construction is deemed unavoidable, they say, it should take into account existing hydraulic conditions and guarantee that they would be maintained after completion.