Is Mexico City Really Sinking?

Mexico City, the capital of Mexico, is indeed sinking. In fact, it is estimated that during the 20th century, the city has sunk approximately 29 to 36 feet (9 to 11 m). Take a dry lake bed, an extremely thirsty population, poor conservation and a seismically active ground underfoot, and you’ve got a serious problem. This thriving metropolis of approximately 24 million (and growing fast) is facing serious problems that threaten infrastructure, water supplies and irreplaceable architecture if the problem is not fixed soon.

Mexico City was originally founded in the 1300s on an island in the middle of Lake Texcoco. As it outgrew the small island, artificial islands were built, as well as a network of canals. Causeways between the mainland and islands were constructed, and are what the modern main roads in Mexico City are built on today. In the 1500s, Spain gained control of the region, and drained most of the lake. A small portion of Lake Texcoco still exists, close to the city. Flooding continues to be a concern due to the fact that the city is below the current level of the lake, and sits in a depression.

The reason why Mexico City is sinking is simple. The city’s main water supply — more than 70% — comes from pumping water from aquifers below the city that were part of the original lake. The water is being siphoned faster than it is replaced by natural sources, such as rainfall. Although the region has significant rainfall, it occurs over short period of time, and the infrastructure is not geared toward collecting and purifying rainwater. The residents of the city consume a great deal of water, much of which is obtained via illegal connections. Not only do they consume a lot of water, a lot is wasted — as much as 40% by some estimates — due to poor conservation, leaky, dislocated pipes and substandard waste treatment.

Evidence of Mexico City’s sinking is everywhere, from cracking streets and sidewalks to moving foundations and crooked balconies. The Angel of Independence monument, completed in 1910, is a stunning example of the city’s problem. In order to access the statue, twenty-three steps have been added because the city has sunk around it. Railroads and subway lines are threatened due to fracturing tracks, and unstable foundations. Another major problem Mexico City faces is the effect of the sinking on its plumbing and sewer systems. Approximately 25% of the population doesn’t even have fresh water plumbing due to dislocated, broken pipes.

The Ecology and Development Center of the Independent National University of Mexico (UNAM), in addition to several other agencies, has suggested that immediate, drastic action should be taken to preserve not only the city’s infrastructure, but also its architectural gems. One project underway is a system to collect rainwater more efficiently to reduce the demand on the underground aquifers. Other projects are promoting water conservationism. Because a portion of Mexico City has been named a UNESCO (United Nations Educational, Scientific and Cultural Organization) World Heritage Site, it is sure to receive the international attention and assistance it needs to save the city.