Ancient Peruvian engineering could help solve modern water shortages


Enlarge / Diversion canals channel water into earth-bottomed infiltration canals like this one, where water can begin to soak into the ground on its way to a pond or basin. (credit: Musuq Briceño, CONDESAN, 2012.)

Rain seldom falls on the desert lowlands of coastal Peru, so people in the area have always depended on the water that flows down from the Andes during the rainy season. But streams in this part of the world come and go quickly, so indigenous people built a system of canals and ponds to channel excess rainwater and create groundwater. Now a group of researchers says that a scaled-up version could help improve Peru’s water management.

Ancient engineers (not aliens)

1,400 years ago, Chavin and Wari indigenous communities on the slopes of the Andes Mountains dug systems of stone-lined and earthen canals to channel excess rainwater from streams to areas where the ground could soak up more of the water. From there, the water gradually trickled through sediment and cracks in the rock until it reached springs downslope. “Water is stored in the soils and travels much slower beneath the surface than it would as overland flow,” Boris Ochoa-Tocachi, a civil engineer at Imperial College London, told Ars Technica. Water that would otherwise have been lost to flooding feeds springs that remain active even into the dry season.

Today, most of these once-widespread canals—called amunas in the Quechua language—lie abandoned or clogged. But in a few rural communities, like Huamantanga in the central Andes, people have used and maintained parts of the ancient amunas for centuries. 11 of the original canals still operate, feeding 65 active springs and 14 small ponds.

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