Nestled between the Pacific Ocean and the Andes mountains, Peru's coastal region relies on surface water from the Andes for drinking water, industry, and animal and crop farming.
The region, which includes Peru's capital city Lima, is often overwhelmed with rain in the wet season -- but by the time the dry season comes, water is scarce.
These factors, together with Lima's rapidly growing population, mean the city struggles to supply water to its 12 million residents during the dry months of May to October.
Now, Imperial researchers and their colleagues at the Regional Initiative for Hydrological Monitoring of Andean Ecosystems in South America, have outlined how reviving ancient water systems could help save wet season water for the dry season, where it is desperately needed.
To do so, they studied a water system in Huamantanga, Peru -- one of the last of its kind.
Boris F. Ochoa-Tocachi, Juan D. Bardales, Javier Antiporta, Katya Pérez, Luis Acosta, Feng Mao, Zed Zulkafli, Junior Gil-Ríos, Oscar Angulo, Sam Grainger, Gena Gammie, Bert De Bièvre, Wouter Buytaert. Potential contributions of pre-Inca infiltration infrastructure to Andean water security. Nature Sustainability, 2019;
DOI: 10.1038/s41893-019-0307-1
Water resources worldwide are under severe stress from increasing climate variability and human pressures. In the tropical Andes, pre-Inca cultures developed nature-based water harvesting technologies to manage drought risks under natural climatic extremes. While these technologies have gained renewed attention as a potential strategy to increase water security, limited scientific evidence exists about their potential hydrological contributions at catchment scale. Here, we evaluate a 1,400-year-old indigenous infiltration enhancement system that diverts water from headwater streams onto mountain slopes during the wet season to enhance the yield and longevity of downslope natural springs. Infiltrated water is retained for an average of 45 d before resurfacing, confirming the system’s ability to contribute to dry-season flows. We estimate that upscaling the system to the source-water areas of the city of Lima can potentially delay 99 × 106 m3 yr−1 of streamflow and increase dry-season flows by 7.5% on average, which may provide a critical complement to conventional engineering solutions for water security.