Lima is one of the world's largest desert cities, so when it rains it -- just kidding, it pretty much never rains. Which leaves Peru's capital city especially vulnerable to water shortages, and the surprising solution might be reviving a system of ancient canals that date back to even before the Incas.
As New Scientist reports, the city's water utility company is now working to conserve ancient stone canals in the Andes mountains called amunas. These canals, long fallen into disuse, were originally built by the Wari culture 1000 to 1500 years ago. The water company will be grouting these long-forgotten canals to make them functional again.
The amunas are actually much than primitive aqueducts bringing water into the city; they're a feat of major landscape engineering. They divert water during the rainy season, when big rivers overfloweth, to springs that then run year-round, essentially turning the landscape into a giant sponge that can be squeezed for water during the dry season.
Water specialists estimate that reviving the amunas can account for 60 per cent of the water deficit during Lima's dry season. And it's a lot cheaper than a fancy new desalination plant. Sometimes, ancient tech can be just as good as high tech.