The ancient pre-Columbian Maya culture was one of the great and flourishing civilizations. Mayans used their traditional ecological knowledge to modify their landscape in stable and resilient ways; in essence, they were early practitioners of ecological engineering.
One example of ecological engineering is their method of rainwater collection. The Maya could not use groundwater, such as natural springs, because it was 500 feet below the surface and they had no technology to reach it.
Ancient Mayan pyramid in present day Belize
So, the Maya depended on rainwater which accumulates in seasonal swamplands, known as bajos, which cover about 40% of the landscape. In modern times, that rainwater evaporates before anyone can use it effectively but the ancient Maya built drainage canals to redirect and reuse the rainwater and converted these wetlands into large agricultural fields.
In order to support such a large population, other methods of agricultural were necessary. The Maya also utilized agricultural terraces, water reservoirs, raised fields, and planted urban gardens. Agroforestry was also practiced that conserved the surrounding rain forest and cycled the agricultural fields through five successional stages: herbaceous stage, two shrub stage, and two forest stages.
However, the Maya ultimately could not sustain their ever increasing population. As the Maya intensified their agricultural production they needed to reduce the fallow times of the fields and they needed additional space so they cleared the rainforest to accommodate urban and agricultural expansion. The widespread deforestation led to increased soil erosion and evaporation which also inhibited sustainable agricultural practices. The Mayans may have inadvertently caused local climate change and drought conditions by converting the wetlands into fields and clearing the rainforest by the slash and burn method.
The Classic Period of the Maya culture significantly declined between the 8th and 9th centuries and most of the Maya cities in the southern Maya lowlands were abandoned. One of the more persistent theories explaining the abandonment is the systemic ecological collapse model. Coupled with drought, ecological collapse due to overpopulation and abandonment of sustainable agricultural practices could have easily manifested into a society turned to turmoil and warfare as food became scarce and urban centers became weak and targets of invasion.