Inhabitants of coastal Peru have always relied on water flowing down from the Andes Mountains during the wet season. Thousands of years ago, indigenous communities created infiltration canals called amunas to allow rainwater to soak into the earth and replenish groundwater sources. Researchers believe that today, similar canal systems could lessen water scarcity in arid areas.
Huamantanga, a rural community in the central Andes, has used ancient amunas for centuries. In fact, today, 11 of the original canals still feed 65 springs and 14 small ponds. A team led by Boris Ochoa-Tocachi, a civil engineer at Imperial College London, recently injected tracer dyes into the canals to determine how much and how quickly waters are able to infiltrate. Over time, the dye emerged at springs downstream, indicating that the amunas system works remarkably well.
As Ars Technica reported, “In some places, it took just two weeks for the dye to make its way through the system and bubble up in a spring; elsewhere, it stayed underground for up to five months before emerging. On average, water took about 45 days to flow through the canals and underground channels to reach springs.”
The team believes that a larger-scale version of the ancient design could prove beneficial for the 12 million residents of Lima, Peru. Using data from Huamantanga that they were able to apply to the Rimac River basin through a computer simulation, researchers found that amunas systems could augment water flow to Lima by about 7.5% during the dry season, while relieving demand on reservoirs, dams, and distribution infrastructure.
Throughout history, civilizations across the globe—from Europe and India to the Middle East—have relied on diversion canals to collect rainwater and replenish water sources. Do you think that infiltration systems could be effective today for storing water and enhancing groundwater recharge efforts?
