Pre-Inca Canal System Uses Hillsides as Sponges to Store Water

[Judi Lynn]

To prepare for a drier future on Peru’s western coast, researchers are turning to techniques of the past.



The village of Huamantanga, in the Peruvian Andes, continues to use and maintain 1,400-year-old amunas, canals that preserve water, to collect and store water during the long dry season. Credit: Diego Pérez/Forest Trends

By Rachel Fritts 30 December 2019

Lima, Peru, which lies on the dry Pacific side of the Andes Mountains, is the second-largest desert city in the world. (Cairo, Egypt, is the largest.) To endure the region’s 7- to 9-month dry season, Lima’s 10 million inhabitants are almost entirely reliant on water collected from the glaciated Andes or transported from the lush Amazon rain forest to the east. But the glaciers are melting, and existing dams and reservoirs, which hold a total of 330 million cubic meters of water, can quench Lima’s thirst through only a single year of drought.

A team of hydrologists, engineers, and social scientists is hoping to strengthen the water security of Lima and other Peruvian cities through analysis of a 1,400-year-old nature-based system developed by pre-Inca mountain communities. The technique uses a canal system that diverts water from streams to small ponds or spreads it over rocky hillslopes that act as natural sponges. This slows the flow of water down the mountains, preserving it into the dry season.

The team’s analysis determined that if the system were scaled up to its maximum capacity, it could divert, infiltrate, and recover up to 100 million cubic meters of water and increase the region’s dry-season water volume by up to 33%. Lead author Boris Ochoa-Tocachi of Imperial College London presented the team’s findings at AGU’s Fall Meeting 2019 in San Francisco, Calif.

Quantifying the Benefit of Green Infrastructure

Like most modern cities, Lima relies on gray infrastructure like reservoirs and dams for water diversion and storage. Gray infrastructure alone, however, has its drawbacks. It is often expensive and challenging to implement. It also has a static threshold, unable to adapt to shifting environmental conditions.

More:
https://eos.org/articles/pre-inca-canal-system-uses-hillsides-as-sponges-to-store-water?utm_source=rss&utm_medium=rss&utm_content=pre-inca-canal-system-uses-hillsides-as-sponges-to-store-water