Learning from our ancestors: Chavin and Wari water systems still work

June 26, 2019 7:28 AM

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. And at a fraction of the cost of developing modern reservoirs. Ancient Peruvian engineering could help solve modern water shortages (Ars Technica; research abstract). Related presentation PDF: Learning from our ancestors: Using modern hydrological techniques to understand ancient water harvesting practices

A longer pull-quote from the Ars Technica article:

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. Eleven of the original canals still operate, feeding 65 active springs and 14 small ponds.

Recently, with help from local non-governmental organizations, people at Huamantanga started enhancing these pre-Incan systems. In most cases, they used concrete to make the upstream section of the canal more watertight so that more water reaches the permeable ground downslope. And when Ochoa-Tocachi and his colleagues injected tracer dyes into the canals and checked to see how much—and how quickly—the dye emerged at springs downstream, it turned out that the amunas system still works remarkably well.

You can find more related research by Boris Ochoa Tocachi and his colleagues from his list of publications, which appear to be focused on citizen science and resource management, particularly hydrology, in and around the Andes (another PDF presentation, from World Water Week 2018)

posted by filthy light thief (10 comments total)

This is very interesting. I have a friend who has spent the past 4 years traveling to Peru to finish up a Peace Corps project that harvests water in fog catchers for coastal villages. I expect she knows of this and I interested to hear more.
posted by OHenryPacey at 8:44 AM on June 26, 2019 [2 favorites]

Previously: qanat water management systems in Iran from ~2,700YA.
posted by migurski at 8:53 AM on June 26, 2019 [4 favorites]

The last Wari post in May introduced me to the wonder of their textiles.
posted by Captaintripps at 8:54 AM on June 26, 2019 [1 favorite]

Much obliged! Ingenious system, although as noted the problem is how to scale it. And it demonstrates clearly how vital it is to keep contaminants out of the ground, although I'd imagine that that's less an issue in those parts of the Andes...? Thanks for posting.
posted by foodbedgospel at 8:57 AM on June 26, 2019 [1 favorite]

I was feeling glum thinking that no project I've contributed to is likely to make any sort of mark a century on, let alone be useful 1,400 years from now.

But then I realized there is a system I've contributed to that might be around that long: The local landfill! I'm as immortal as plastic now.

That's the best kind of surgery, right? So it's probably the best kind of immortality too.
posted by Western Infidels at 9:09 AM on June 26, 2019 [5 favorites]

Adding a swale to your yard is an easy way to start harvesting water like the ancients.
posted by ContinuousWave at 9:44 AM on June 26, 2019 [1 favorite]

harvests water in fog catchers

Wow. Real-world in-use windtraps. So cool.
posted by porpoise at 11:40 AM on June 26, 2019

Refilling Lake Chad With Water From The Congo River Using Solar Power

This is a similar plan, moving water into a different watershed and then letting the topography do the rest.
posted by joeyh at 12:02 PM on June 26, 2019 [1 favorite]

Meanwhile, we can now expect pumping from freshwater aquifers under the briny sea.
posted by pracowity at 3:45 AM on June 27, 2019

Oh, dear. Is that link broken? More generic news link here.
posted by pracowity at 4:34 AM on June 27, 2019