A city somewhere in the world may be following Atlantis' footsteps in the coming years. It is not just because of the rising sea levels experienced worldwide. It may add to it, yes, but there is something more alarming reason that needs to be addressed. It may be because that city itself is sinking fast.
Scientists recently bared that the ground, especially in coastal areas, is dipping ten times faster than the rising sea levels and this is mainly due to over population and excessive groundwater extraction.
Coastal mega-cities such as Jakarta, Dhaka, Ho Chih Minh City, New Orleans, and Bangkok are more prone to land subsidence because the cities are erected on soft soils. With the presence of the rising sea levels around the globe, these cities may be submerged in the waters lest necessary actions are done.
"Land subsidence and sea level rise are both happening, and they are both contributing to the same problem - larger and longer floods, and bigger inundation depth of floods," said the study's lead author Gilles Erkens of the Deltares Research Institute in Netherlands.
In a paper [pdf] presented at the recent European Geosciences Union General Assembly, Erkens, who presented the study on behalf of his team, said that while land subsidence is caused mostly by natural causes, it is aggravated by the human-induced activity happening over time.
Excessive groundwater extraction after rapid urbanization and population growth is the main cause of severe land subsidence," wrote Erkens in their abstract, while noting a decade-long practice of ground water extraction in Tokyo that sunk the city by two meters.
He added that there are ways to put an end to the extraction, citing Japan's efforts to impose new restrictions.
The huge population, meanwhile, is the main problem of Indonesia's largest city of Jakarta. From only 500,000 inhabitants in the 1930s, the city grew to 10 million at present, requiring more water to be pumped out, thereby hastening land subsidence to six and a half feet.
Should such situation persist, Erkens and his team warned that this may hurt the economic state of the nation, estimating costs of damages in infrastructures and roads to a billion dollars every year due to larger flooding.
Building higher seawalls can only do so much, Erkens says, but it will be only overrun by the rising sea level eventually, the same conundrum that has been troubling New York City recently.
