Travel

Why are cities sinking?

We look at some of the world’s sinking cities at risk of vanishing beneath the waves, and possible solutions to this pressing problemMonday, 8 April 2019

By National Geographic Traveller (UK)
Venice, Italy - February 2017 - "Hands" is the latest masterpiece by the artist Lorenzo Quinn. This majestic sculpture was installed on Grand Canal simultaneously with the inauguration of the Biennale of Arts. A gondola with the gondolier and his clients is approaching the mooring by the big sculpture.

Cities are slowly sinking for a number of reasons, both man-made and natural. These range from rising sea levels to subsistence in metropolises caused by the weight of buildings and people, and the interaction of geological and climatic factors. The Iranian capital of Tehran is sinking at a particularly alarming rate, with around 10% of its area affected. The airport is also subsiding at a rate of two inches a year. 

Across the pond, NASA/European Space Agency data suggests parts of a 444-mile aqueduct in California sank over 23 inches from 2013 to 2016. California’s San Joaquin Valley — whose cities include Stockton and Fresno — is sinking by the same amount per year, too.

Cities are coming up with innovative ways to keep themselves above ground, however. In Bangkok, Chulalongkorn University created an 11-acre park designed to drain millions of litres of water, while Rotterdam has turned car parks into emergency reservoirs. Venice — a city notorious for its subsidence due to being built on soft soil — is tackling the issue by using lighter materials to construct buildings and Tokyo has set limits on the extraction of groundwater, stopping sinking completely. 

Five other sinking cities:

Alexandria
Egypt’s main port city could be completely submerged should water levels rise by 6ft

Miami
Experts forecast that by 2040, the sea level in parts of Miami could rise between 13 and 34 inches

Tianjin
Since the 1950s, parts of the Chinese city’s coastline have sunk by up to 9ft

New Orleans
Some coastal areas are sinking by up to 2 inches a year

Jakarta
Home to nearly 10 million people, the Indonesian capital is one of the fastest-sinking cities in the world, lowering at a rate of 9.8 inches a year. Researchers say parts of the city could be entirely submerged by 2050

Source: GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre

Published in the March 2019 issue of National Geographic Traveller (UK)

 

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