The Khmer built, for example, a massive stone structure to divert the Siem Reap River from its old bed through the center of the city. Other sites have stone structures built into the walls to manage the inflow and outflow of water, he said.
The system was complex enough that the Khmer could have grown rice throughout the year and not just during the rainy season, Evans said. It is not yet clear if they did so, however.
For The Record
Los Angeles Times Wednesday, August 15, 2007 Home Edition Main News Part Page News Desk 1 inches; 52 words Type of Material: Correction
Angkor: A photo caption in Tuesday's Section A with an article about the ancient Khmer city of Angkor in Cambodia said the temple in the photo was Angkor Wat. It was the Bayon temple. The article also gave the area of the city as 115 square miles. It is 1,350 square miles.
"The intentional movement of earth to create the whole water system is just really mind-boggling," Saturno said. "It was an enormous undertaking" that required not just administrative skills, but also engineering know-how and massive amounts of physical labor.
But in the end, maintenance became too labor-intensive, Evans said. As trees were removed from the landscape, sediment began accumulating in the canals at a rate more rapid than it could be removed. Many dike walls collapsed, although it is not yet known when that occurred.
"We're going now and excavating [the sites] on the ground, and trying to get a grip on when they happened -- whether they were a precursor of the decline, a symptom or the system gradually falling into ruin after they left," he said.