February 2, 2022 1254 PM
Learning from other arid regions around the globe – Peru
It seems like we’re constantly hearing about places in the world on the verge of running out of water. Cape Town, in South Africa — one of the world’s driest countries — remains critically at risk of running out of drinking water. Perth, on the west coast of Australia, is now dependent on desalination for 50 percent of its drinking water supply. Cairo, Egypt is facing acute water shortages with enormous impacts on the Nile River, which is sourced from the south. Meanwhile, the Sahara Desert continues to expand southward at a rate of about 30 miles a year.
So what can we, who live in the Chihuahuan Desert, learn from other arid regions of the planet before we potentially share their fate?
According to a recent BBC article by Erica Gies, author of the upcoming book Water Always Wins, Peru provides a promising lesson. Lima, the capital, is situated between the Pacific Ocean and the Andes Mountains in one of the driest desert systems in the world: the Sechura-Atacama Desert. With annual rainfall of just 0.5 inches per year, Lima is heavily dependent on mountain rivers, making it one of the most water-insecure places on earth. The local water utility, Sedepal, is only able to supply water to its customers for about 21 hours a day. A 2019 report by the World Bank found that Lima’s current strategies for managing drought, including dams, reservoirs and underground storage below the city, will be inadequate by 2030.
In response to this scarcity, the national government began requiring utilities to invest a portion of their revenues in “natural infrastructure.” Instead of conventional approaches that “tend to confine water and speed it away, erasing natural phases when water stalls on land,” nature-based solutions (a concept that Gies refers to as “slow water”) actually “make space and time for these slow phases [to occur].” One such approach involves the revival of ancient water canals constructed by the Huari people called amunas from a Quechua word meaning “to retain.” These stone canals channel flows from mountain streams during the wet season and direct them to “natural infiltration basins.” In a process known locally as sembrar el agua or “planting the water,” the flows soak into these basins and move slowly underground through gravel and soil, emerging downhill several months later in spring-fed ponds and streams, which the villagers use to irrigate their crops. If properly harvested, these waters could greatly enhance Lima’s water supply during the dry season. But first, the network of amunas in the highlands above the city needs to be restored –– a perfect candidate for the “natural infrastructure” improvements now required by national law.
Because “[u]rbanites tend to discount the expertise of rural and indigenous people,” Gies reports, scientists worked with villagers to install sensors to measure the flows entering the infiltration basins from the amunas and added tracers to the water itself. Using highly sensitive detectors, the scientists were able to confirm that the water reemerging from the ground far away was in fact the water from the amunas and that the indigenous technique was actually “very accurate.” According to Boris Ochoa-Tocachi, an advisor to the project, the data “shows that we can use indigenous knowledge to complement modern science to provide solutions to current problems.”
“Although every country has unique water issues, landscapes and cultures,” according to Gies, “other places can learn from Peru’s experience … Human activity that degrades land’s ability to hold water can be reversed, whether it be deforestation [in Kenya] … or overgrazing in the western United States.” Stay tuned for future issues of “Our Water Matters,” where we will explore local efforts to repair and enhance our own “natural infrastructure” right here in the Big Bend.
Trey Gerfers is a San Antonio native and serves as board chairman of the Presidio County Underground Water Conservation District. He earns his living as a translator of technical documents from German to English for the German and Swiss pharmaceutical and medical-science industries. Trey has lived in Marfa since 2013. He can be reached at [email protected]
