Pedro Villegas, 9, rides a burro in the Monte Desert of Argentina. As the burro walks forward, it activates a pulley connected to a well. Huarpe people like Pedro, whose family has lived in this desert region for centuries, depend on wells connected to the water table below the desert floor.

Scientists have found that the level of the water table has declined in recent years, perhaps due to a robust wine industry that requires large quantities of water.

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