28 densely populated cities predicted to be flooded

Dozens of densely populated American megacities are gradually sinking underground, threatening the safety of 34 million residents.

According to a new study by Columbia University, the main cause of ground subsidence is excessive extraction of underground water. Notably, it's not only coastal areas that are sinking most rapidly, but also cities deep within the country.

Houston has become the absolute "leader" in sinking speed - almost half of its territory is sinking more than 5 mm annually, with some areas subsiding up to 5 cm per year. Dallas and Fort Worth follow with rates of about 4-5 mm per year. Also at risk are LaGuardia Airport in New York, areas of Las Vegas, Washington, and San Francisco.

"As cities grow, more territories will expand into subsiding regions," warns the study's lead author Leonard Ohenhen. "Over time, this could create a load on infrastructure that exceeds its safety limits."

Scientists used satellite data to create detailed subsidence maps for all US cities with populations over 600,000. Although only about 1% of the territory in the 28 studied cities experiences critical subsidence, these zones are typically located in the most densely populated areas where thousands of buildings are concentrated.

Buildings in San Antonio (every 45th building), Austin, Fort Worth, and Memphis are at the greatest risk.

In addition to groundwater pumping, other factors affect subsidence: consequences of ancient glacier melting, the weight of urban structures themselves, and new construction. Researchers urge city authorities to use the obtained data to develop strategies to reduce the risks of flooding and infrastructure destruction.