Mexico City, home to 22 million residents, is sinking at a rate of 23.8 centimeters per year. The subsidence stems from decades of excessive groundwater extraction, raising concerns about a potential water supply cutoff as drinking water sources deplete.
According to CNN on Thursday, observations from NASA's advanced radar system confirmed ground subsidence of more than 1.27 centimeters per month in Mexico City. The movement is pronounced enough to be detected from space, giving Mexico City the dubious distinction of being one of the fastest-sinking capital cities on Earth.
Mexico City was built across highland lakes. With 22 million people densely packed into the city, approximately 60% of its drinking water currently comes from ancient aquifers. The problem is that decades of over-pumping groundwater have caused the overlying strata to settle. Unchecked urban development has further accelerated the pace of subsidence.
The NISAR satellite, jointly developed by NASA and the Indian Space Research Organisation (ISRO), captured the situation in precise detail. Satellite observations showed that during the dry season from October last year to January this year, parts of downtown Mexico City sank by approximately 2.2 centimeters per month. On an annual basis, that translates to a rate exceeding 23.8 centimeters. The subsidence was found to be particularly severe near Benito Juárez International Airport.
"Mexico City is one of the most prominent areas for ground subsidence," said David Bekaert of the NISAR science team. "Through the NISAR satellite, new discoveries tracking subtle movements of the Earth's surface around the world will continue to emerge."
An even bigger problem looms. Warnings have emerged that if the current structure of continuous groundwater pumping is maintained, the drinking water source itself could be completely depleted.
If the water source runs dry, it could lead to an unprecedented water cutoff in which the city's water supply is entirely halted. As the ground continues to sink, the aquifers also suffer damage that is difficult to reverse, creating a vicious cycle. Analysis is gaining traction that the very foundation of life for 22 million people is now under threat.
