The past always comes back, the saying goes. Centuries ago, the Mayan Empire faced an annual dry season that lasted five months. River levels were dropping, the waters were becoming murky, and diseases were rampant. At a critical moment, Mayan engineers had a brilliant idea: they created a sophisticated system of urban deposits that sustained the supremacy of this culture for more than 1,000 years.
The surprising thing is that, in the 21st century, this solution found in the tropical lowlands of southern Central America could be the solution to future water scarcity, as explained by researchers from the University of Illinois in an article published in the journal Proceedings of the National Academy of Science (PNAS).
Anthropologist Lisa Lucero, lead author of the study, explains that these ancient reservoirs that provided drinking water to a large number of people, acted very similar to modern artificial wetlands, which depend on physical and biological processes to filter water without need. of chemical treatments.
“To compensate for the seasonal scarcity of water, the ancient Mayans of the Classic period (from 250 to 900 AD) built reservoirs that were the main source of water during the dry season,” says Lucero.
Among the largest of these reservoirs was the one that supplied the city of Tikal, which could hold more than 900,000 cubic meters of water. By expert calculations, this was more than enough to meet the daily drinking, washing and cooking needs of the 80,000 people who occupied the site during its peak.
Previous analyzes of the Tikal deposit have revealed that its base was lined with volcanic zeolite sand, which was imported from about 30 kilometers away and served to filter out impurities and pathogens. In addition to this natural filtration system, the Mayans also used aquatic plants such as cattails, reeds, and hyacinths to prevent water from stagnating.
These plants remove nutrients such as nitrogen and phosphorus from the water, thus limiting the growth of dangerous algae. According to Lisa Lucero, the water lily was a particularly revered plant in ancient Mayan culture due to its association with clean water and was therefore linked to royalty.
“Kings and water lilies were represented together in monumental architecture, stelae, murals and even portable objects. The Mayan monarchs wore water lily headdresses and there are inscriptions that mention Nab Winik Makna (Lords of the water lilies) to refer to the kings and Ah Nab (people of the water lily) to refer to the Mayan nobility," he points out.
To encourage the growth of water lilies, the Mayans lined the reservoirs with clay. In turn, the lilies shaded the reservoirs, kept the water cool and prevented the accumulation of algae. Additionally, they provided habitat for dragonflies, fish and turtles, which fed on mosquitoes and other harmful insects.
At the same time, collecting fish droppings and dead aquatic plants would have provided the Mayans with high-quality nutrients for their agricultural lands. Lucero says artificial wetlands similar to those created by the ancient Mayans could “contribute to ensuring access to drinking water for all.”
"These reservoirs do not require the use of chemicals or fossil fuels for maintenance and, after the initial labor-intensive production, they become self-sufficient with some maintenance," concludes the University of Illinois anthropologist.
