The decline of the Mayan civilization after the 9th century has long remained, and likely will remain, a mystery. As with any such situation, there were likely a lot of factors, but one of them might have been water. Computer models developed at Technical University Wien in Austria have shown that Mayan water engineering may have inadvertently led to the culture’s decline.
The Mayans built large reservoirs to retain water in case of dry periods, which certainly helped in the short run by allowing them to provide for established water needs and still maintain population growth after droughts. But, those same reservoirs may have lulled the Mayans into a false sense of security during longer periods of water scarcity. If the Mayans kept consuming water at normal rates during and after droughts, they could have run low on water before they could replenish their reservoirs.
The model shows that water engineering is more complicated that humans have generally seen it as being. Systems that seem to work, such as the Mayan reservoirs, might not work as well as we think, when faced with longer than average scarcity.
This is an important lesson for modern civilization too. Global climate change is impacting human access to fresh water, with rivers drying up and the like. Desalination technology has not yet reached a level where we can reliably use it to increase our water sources, and even when it does, water will still be evaporating at a higher rate than it has been for much of the time we’ve been on the planet.
In order to prevent what happened to the Mayans from happening to us, we need to work on developing novel ways to manage existing water resources. It’s important not to rely too heavily on one model, only to have that model fail us when droughts begin to get even worse.