Increasingly cities in the world are affected by floods and land subsidencewhich increases the risk that millions of people will have to abandon their homes. The intensive groundwater extraction, global warming and the pressure of rapid urbanization are transforming many cities in increasingly vulnerable spaces.
According to the UN-Habitat World Cities Report, more than 1.4 billion people already reside in areas located less than five meters above the sea. sea levela figure that continues to grow and that exposes large cities a unprecedented flood risks, structural damage and forced displacement.
Coastal cities and low-lying areas face an increasingly uncertain future.He land subsidenceknown as subsidence, affects cities in Asia, Africa, Europe, Latin America and the United States. In many cases, this process occurs as a result of the sea level rise and for the human pressure on water resourcesespecially in coastal areas, deltas and densely populated low-lying areas.
One of the most critical cases is Jakartain Indonesia. There, the excessive groundwater extractionadded to weight of the infrastructure urbana and the lack of planning, caused many areas in the north of the ciudad will remain below the sea level.
Despite projects in the city to reduce flood risks such as the «Giant Sea Wall» and the partial transfer of the capital to Nusantara, the threat remains latent.
Jakarta, one of the cities most affected by floods.In Shanghailocated in the Yangtze River Delta, the subsidence history of the land and the advance of the sea threaten one of the largest urban economies in the world planet. The report of UN-Habitat warns that, even with coastal defenses, the city faces chronic flooding that affect millions of inhabitants.
Europa It also shows warning signs. Venice It is considered the European city with the highest risk of being submerged. The combination of natural subsidencehuman activity and the Adriatic sea level rise intensified the phenomenon of High water.
In 2020, the ciudad inaugurated the MOSE mobile barrier system to contain the floods by high tide. Even so, international organizations warn that it could be surpassed if the sea level continues to rise.
Venice fights against the advance of water and the sinking of the soil.In Africa, Cairo y Alexandria suffer accelerated erosion of the delta Needwith direct impacts on housing, agriculture and food security. In Asia, Ho Chi Minh Cityin it delta del Mekongfaces increasing risks due to disorderly urbanization and agua stored under tierra.
Netherlandswith cities like Amsterdam and Rotterdamrepresent a different model: much of their territory is already under the sea levelbut the country invests constantly in discsadvanced management agua and amphibious architecture. Even so, climate reports ensure that extreme scenarios could overcome current defenses.
Houston, United States: More than 40% of the city is declining at an accelerated rate.In USA, A recent study in Nature Cities revealed that the top 28 cities present some degree of sinking. Houston leads the ranking by groundwater extraction and oil activity, while New York registers slower but constant declines, aggravated by the weight of its infrastructure.
The UN-Habitat World Cities Report warns that, without profound reforms in urban and water management, The risks associated with land subsidence and flooding will continue to intensify in the coming decades.
