Mexico City sinks up to 50 cm yearly as drained Lake Texcoco clay compacts
This digest was compiled by AI from multiple sources — links to the originals are below.
Mexico City is sinking at rates up to 50 centimeters per year, with cumulative elevation loss in the worst areas reaching nearly 39 meters since 1950. The subsidence is driven by groundwater extraction that drains and compacts the ancient lakebed clay beneath the city. Satellite radar and GPS measurements confirm the trend has held broadly steady for over seven decades.
Key Facts
- Subsidence rates in Mexico City have held broadly steady since 1950 and reach 50 centimeters per year, with cumulative elevation loss in the worst areas running to nearly 39 meters.
- Roughly 70 percent of Mexico City's drinking supply now comes from wells sunk into the basin, some three kilometers deep.
- A separate group using Sentinel-1 radar and GRACE gravity data measured more than 35 centimeters a year of sinking inside the city, plus close to two centimeters of annual uplift in the surrounding hills.
- The Gran Canal del Desagüe, inaugurated by Porfirio Díaz in 1901, gave the closed basin a permanent drainage outlet after centuries of work that began with the Tajo de Nochistongo trench in 1607.
Draining Lake Texcoco
The Spanish colonial administration viewed Lake Texcoco as an accounting problem that ruined property and reduced rent revenue. From 1607, forced Indigenous labour cut the Tajo de Nochistongo, a trench roughly 20 kilometers long and 60 meters deep, through the basin wall. The drainage effort culminated in the Gran Canal del Desagüe, inaugurated by Porfirio Díaz in 1901, which gave the closed basin a permanent outlet. With the lake gone and the springs spent, Mexico City turned to groundwater, and roughly 70 percent of its drinking supply now comes from wells sunk into the basin, some three kilometers deep.
Satellite Measurements
Estelle Chaussard and colleagues stitched together 115 years of ground survey data with 24 years of satellite radar and 14 years of GPS. Writing in the Journal of Geophysical Research: Solid Earth, they report that subsidence rates have held broadly steady since 1950 and reach 50 centimeters a year, with cumulative elevation loss in the worst areas running to nearly 39 meters. A separate group using Sentinel-1 radar and GRACE gravity data measured more than 35 centimeters a year of sinking inside the city, plus close to two centimeters of annual uplift in the surrounding hills. The uplift in the surrounding hills is the crust flexing upward as the weight of all that groundwater leaves the basin.
Clay Compaction
Under Mexico City lies an aquitard, a thick bed of lakebed clay that holds enormous quantities of water but releases it grudgingly. Dropping the pressure in the aquifer below causes that clay to slowly drain and then shrink. Squeezed clay does not spring back, so switching off the pumps would not reverse the subsidence that has already occurred.
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Mexico City sinks up to 50 cm yearly as drained Lake Texcoco clay compacts
