TWO enormous masonry structures discovered near Cambodia's fabled temples of Angkor Wat provide rock hard evidence that the once powerful Khmer kingdom vanished because of over-building, environmental damage and climate change. One of the newfound structures was a 40m by 80m spillway. The other was a 100m by 40m outlet channel that, like the spillway, was part of the elaborate water system that served the sprawling agricultural city of Angkor.
"There are considerable implications for our understanding of our own water management systems," cautioned Sydney University archaeologist Roland Fletcher, head of the team that discovered the huge objects. "These two structures demonstrate very high levels of hydraulic engineering," added Associate Professor Fletcher, director of the Greater Angkor Project, a five-year collaboration between the university, French researchers and the Cambodian agency managing Angkor.
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But Professor Fletcher's group suspects that the city died when it could no longer support the rice-growing economy that fed it. That happened as a consequence of the city's success. As Angkor grew, more land was cleared for rice paddies, increasing soil erosion into the irrigation canals. Silt built up, choking the water system and demanding increased time and resources to keep the network flowing. The final kick came from abrupt changes in the monsoon rains which filled the great lake Tonle Sap, east of Angkor. The lake fed into the meticulously organised water management system and provided fish for the burgeoning population.
According to Professor Fletcher, discovery of the spillway and the outlet support their argument as they demonstrate how massive, but inflexible, the water infrastructure was. "It became like a gigantic straightjacket," he said. "Like the spillway, the outlet channel was (deliberately) blocked and drastically modified, suggesting the water management newtwork began to break down later in the history of Angkor," Professor Fletcher said.
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