The Mayan civilization existed for several millennia leaving plenty of abandoned cities and cultural monuments on the Yukatan peninsula. The society suddenly passed after people left their cities. Scholars have long discussed the reasons for both the rise and demise of the Mayan civilization. In 2012, scientists discovered a complex system of water reservoirs and tunnels proving the hypothesis that droughts led to the decrease in population of many Mayan cities.
But there is strong evidence that an innovative reservoir system which allowed Tikal to grow to a metropolis and flourish could have aggravated the dry spells.
Linda Kuil and her colleagues from Vienna University of Technology studied the link between water shortage and the Mayan decrease. They created a computer model of a typical Mayan city populated with 80,000 to 100,000 people. The model included several other models of different aspects, such as the relationship between water level and survival, between population growth and food/water resources, etc.
As it turned out, the system worked well during short droughts only if the water was abundant. Otherwise, a small decrease in water level resulted in a dramatic population drop.
“Additional storage brings benefits when the rains come, allowing the society to grow larger, but when the rains fail, the dependence of society on the additional water makes them more susceptible to population decline”, Linda Kuil says.
So, the reservoirs were not a means of survival but a reason for the death of people during long droughts. There are several reasons for that. In particular, people exceeded the population density and consumption relying on water in the reservoirs which could be scarce. As a result, in the event of long severe droughts such cities lost more people than those that did not have reservoirs at all. It sheds light on why residents abandoned all big Mayan cities that never recovered while smaller settlements survived.