Given Mexico City’s original geography, its lack of water may seem strange. The city was built on an island surrounded by a large natural lake basin. But when the Spanish colonised Mexico in the 1500s, they dried out the lake to build a bigger city.

This means that deep underground, Mexico City has fresh water reservoirs – which the city still depends on for about 40% of its water. In theory these natural aquifers should be replenished by rainfall. It can seep through water containment holes like these pictured here in this deforested patch of land.

But the shortage of water in the city means these natural water reserves are being emptied at a rate faster than they can be filled, especially during months of prolonged drought in the dry season.

“We are exploiting our local aquifers at a very high rate,” says Kramer. “At the same time, we haven’t invested enough resources to have a robust monitoring system. So there’s a lot of uncertainty how the local aquifers work.”

His team suggests that the aquifers could be depleted in 30 to 50 years, if current exploitation trends continue.

(Photo credit: Carlos Cazalis/INSTITUTE)