Mexico City residents have dug several ditches around and inside the area Lake Texcoco occupied for several centuries. In 1607, they dug a ditch north of the lakes of the Central Mexican basin to try to drain all of their water and dry up new stretches of land for urbanization. In 1629, a great flood caused its collapse. Its frail structure was erased as the water level rose in the rivers and lakes that took up great spreads of land in the Valley of Mexico. After the failure of the first ditch, a new canal was dug to drain the metropolitan area in the early 20th century. This subterranean Great Canal crossed the lake land south to north, directing the lacustrine water towards the Tula River, into the Mezquital Valley, in the state of Hidalgo.
As the city grew, a series of underground aquifers shrank in size. Their water was extracted through shallow wells: a well is a sort of vertical ditch that opens the land until it reaches down into one of the reservoirs. As the ground sank as a result of the vertical channels pumping water out, the Great Canal yielded, sloping the wrong way, causing the water’s return to the lakes. [...]