The temples of Angkor are architectural marvels and international tourist attractions. But in an August paper in the Proceedings of the National Academy of Sciences, archaeologists from Australia, Cambodia, and France reported using a combination of ground surveys and aerial scans to create a broader, more comprehensive map of the ancient Cambodian ruin, confirming that it was once the center of an incredibly vast city with an elaborate water network.
Lead researcher Damian Evans, an archaeologist at the University of Sydney, says the true extent of the city is apparent only from above. Between A.D. 800 and 1500, Angkor’s complex canals, roads, irrigated fields, and dense settlements sprawled across more than 1,160 square miles, almost the size of Rhode Island—and far beyond the area protected within the UNESCO World Heritage Site’s zone today. The city was the preindustrial world’s largest urban complex, made possible by some of the most complicated hydraulic works the world had ever seen.
American technology played a critical role in the analysis. NASA’s Jet Propulsion Laboratory flew a 747 specially equipped with ground-scanning radar over the site, teasing out subtle differences in elevation and soil content. Added to conventional aerial photography and confirmed through ground surveys, the radar images showed that Angkor was unsustainable. Stripping off the area’s natural forest cover exposed the complex irrigation systems to unexpected erosion and flooding. “They very intensively reengineered the landscape wherever they went,” Evans says. “When you start creating these incredibly elaborate engineering works, it’s inevitable that you create problems. Angkor engineered itself out of existence.”
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