Angkor Wat's lost city

THE Angkor Wat in Cambodia is the centre of a much bigger community than once thought.

The mediaeval Khmer city of Angkor was the largest pre-industrial metropolis in the world, with a population of nearly one million and an urban sprawl that stretched over an area similar to modern-day Los Angeles, researchers reported on Monday.

Now obscured by vegetation and low-lying clouds, the ruins surrounding the temple were once thousands of houses, roads, man-made ponds and canals, according to a report in the Proceedings of the National Academy of Sciences.

Archaeologist Damian Evans of the University of Sydney, lead author of the paper, said: "We now know that instead of being just temples, Angkor was actually a continuous and interconnected network of temples and small-scale residential features like small village ponds."

The city's spread was made possible by a sophisticated technology for managing and harvesting water for use during the dry season, including diverting a major river through the heart of the city.

But that reliance on water led to the city's collapse in the 1500s as overpopulation and deforestation filled the canals with sediment, overwhelming the city's ability to maintain the system.

During the six centuries that the city thrived, it was unparalleled, particularly because it was one of the few civilisations that sprang up in a tropical setting.

"The scale is truly unparalleled," said archaeologist William A. Saturno of Boston University, who was not involved in the study.

"Forest environments are not good ones for civilisations... because they require intensively manipulating the environment. Angkor is the epitome of this, and it is going to be the model for how tropical civilisations are interpreted." The new data comes from an unusual agglomeration of both old and new technologies.

The core data came from a synthetic aperture radar unit flown on the space shuttle in 2000 and managed by Nasa's Jet Propulsion Laboratory in La Canada-Flintridge, California.

The radar pierced low-lying clouds and vegetation to give an accurate picture of soil density, local structures and moisture in soil, which reflects growing conditions.

The images clearly revealed, for example, the characteristic moat-enclosed local temples and artificial ponds used for water storage and irrigation.

This data was supplemented with photographs taken from ultralight aircraft flown over the city at low speeds and altitudes.

Finally, the researchers used motor scooters to traverse the city and closely examine sites revealed on the radar images. But so many sites have been revealed, Evans said, that researchers are only part way through the process.

The group, collectively called the Greater Angkor Project, released a partial map three years ago.

The new one released on Monday contains, among other things, an additional 1,000 sq km of urban area, at least 74 long-lost temples and more than 1,000 newly recognised artificial ponds.

Angkor was the capital of the Khmer empire, which got its start in AD 802 when the god-king Jayavarman II declared the region's independence from Java. At its height, the empire ruled not only Cambodia but also parts of modern-day Laos, Thailand and Vietnam.

It is perhaps best known for the magnificent temple Angkor Wat, built by King Suryavarman II in the early 12th century.
AP, LAT-WP, REUTERS