The ancient Maya are probably the most well-known of the Pre-Columbian civilizations of Central America. The Maya are especially known for their monumental architecture, writing system, calendar, astronomy and mathematics. But among their greatest achievements was also their water management system that made it possible for the civilization to thrive on the Yucatan Peninsula with its lack of surface water and six-month dry season.
The Maya water management system relied mainly on harvesting and storing rainwater. This allowed the Maya to survive the dry season, but the success of the system and the resulting growth in population also made the Maya vulnerable to drought. Moreover, while the Maya had mastered water management, they were mismanaging another part of the environment, namely forests. There are dozens of theories that try to explain why the Maya civilization collapsed, but drought amplified by deforestation is one of the most likely causes.
Water in the Yucatan Peninsula
Yucatan Peninsula, the home of the ancient Maya, is an area that contains parts of modern-day Mexico, Guatemala and Belize. Geologically speaking Yucatan consists of porous limestone with a thin layer of soil on top. Rainwater passes easily through the soil and the limestone, and because of this there is nearly a complete lack of surface water on the peninsula.
As the rainwater passes through the limestone, some of it comes to rest in underground caves. If the limestone on the surface breaks, the water-filled cave is exposed and forms what is called a cenote. The Maya took advantage of these cenotes as water sources wherever possible.
Where there were no easily accessible underground water sources, the lack of surface water coupled with a six-month dry season and frequent droughts made agriculture very difficult. Thus, in order to survive the Maya had to develop their own water management strategies. The fact that the Maya managed to build a thriving civilization in this environment for 2000 years is testament to their skills as engineers.
Maya water management and engineering
Where natural caves were unavailable, the Maya turned to man-made cisterns. These cisterns, knowns as chultuns, were bottle-shaped underground water storage chambers that were lined with lime plaster to prevent water from seeping out. Connected to the cisterns was a system that harvested and transported rainwater, and the design varied between different cities. The cisterns then stored rainwater from the wet to the dry season.
One of the cities with the most advanced water management strategies was Tikal, located in the north of modern-day Guatemala. At Tikal buildings, paved roads and plazas were connected to canals that would direct as much rainwater as possible to man-made reservoirs. These reservoirs conserved water to the dry season and made it possible for the city’s high population to survive periodic droughts. Tikal also had a huge dam which is the largest known hydraulic project built by the Maya, and there is evidence that the Maya used sand to filter water.
Another Maya city with and intricate water management system was Palenque in southern Mexico. Palenque was unique in the Maya world because natural springs made water easily available, and instead the city had to be protected from flooding. Here the Maya built underground aqueducts that would direct water from natural springs to where it was wanted. At Palenque there is even evidence that the Maya were able to work with water pressure to create fountains or possibly even to flush toilets.
Deforestation, drought and the collapse of the Maya civilization
But even all their elegant engineering and science couldn’t save the ancient Maya. The Classic Maya civilization started to collapse between the 8th and 9th centuries when cities like Tikal and Palenque were abandoned. There is no scientific consensus as to why the civilization collapsed, but likely theories include war, civil unrest, environmental degradation, or a combination of factors like these. One of the more likely theories is persistent droughts.
The Maya had also deforested large parts of the jungle, and one theory states that this deforestation is part of the reason why the droughts hit so hard. Deforestations was done to make space for agriculture, but wood was also necessary for creating the monumental construction the Maya are best known for. The construction of pyramids, temples and even water reservoirs required vast amounts of lime to make plaster and mortar, and making lime required burning limestone. To produce enough plaster for one square meter of wall would require burning 20 large trees, hence the need to cut down forests.
The crops planted on the cleared land had a lighter colour than the forests, and this meant that the land now absorbed less solar radiation and hence there was less evaporation and rainfall. This effect wouldn’t have been sufficient to cause droughts, but it would have exacerbated natural droughts when they came. It was no longer possible to fill the water reservoirs during the rainy season, and the lack of water would have made it difficult to grow enough food for the large population, which in turn could have led to civil unrest or diseases, or both. Deforestation also would have contributed to increased erosion and soil degradation.
Once the Maya civilization collapsed, forests slowly returned to the Yucatan. But deforestation threatens the region again today as the impoverished and growing population searches for new agricultural lands, especially in Guatemala. At the same time, droughts like the ones that destroyed the Maya are predicted to become more common due to climate change. Can we learn something from the fate of the ancient Maya before it’s too late?