BEIJING, Aug. 15 (Xinhuanet) -- NASA satellite ground-sensing radar data has helped researchers find evidence that Cambodia's Angkor Wat temple was the center of one of the largest cities of the pre-industrialized world, covering an area of almost 400 square miles (1,000 square kilometers).

    For comparison, Philadelphia covers 135 square miles, while Phoenix sprawls across more than 500 square miles, not including the huge suburbs. Each has about 1.5 million residents in the city limits.

    "In terms of population, however, Angkor would only have had a few hundred thousand people," said study team member Damian Evans, an archaeologist at the University of Sydney in Australia. "There were cities with much larger populations — for example, in China — before, during and after the Angkor period."

    The work, detailed in the Aug. 14 issue of the journal for the Proceedings of the National Academy of Sciences, provides fresh evidence for an idea put forward more than 50 years ago — that Angkor relied on a complex irrigation system consisting of linked ponds and that the city's downfall might have been the result of land overexploitation.

    Angkor was the capital city of the Khmer empire from the 9th to the 16th centuries. The now-crumbling and decadent temple, Angkor Wat, was constructed in the 12th century at the bidding of one of its kings.

    The new maps show that Angkor's water system consisted of canals in the North that funneled water into massive reservoirs in the city's center where the temple resided. "From there, a series of distributor canals dispersed the water through the southern parts of Angkor and down towards the lake," Evans explained.

    In the 1950s, the late archaeologist Bernard-Philippe Groslier speculated that traces of a hydraulic network were part of an ancient irrigation network that ferried water to farmers in the city's suburbs. Groslier also argued that the breakdown of the network, triggered perhaps by overexploitation of the landscape, was implicated in Angkor's downfall.

    Supporting Groslier's hypothesis, the new maps and excavations reveal breaches in dykes and attempts to patch up the system. Whether such phenomena were the cause, a symptom or a result of Angkor's decline remains to be determined, Evans said.

    (Agencies)