Ancient Capital Wilted When Water Ran Low

Angkor Wat in 1866

January 2, 2012
By HENRY FOUNTAIN
The New York Times

Angkor, the ancient city in Cambodia that was the seat of the Khmer empire, flourished from the 9th to the 15th century. Today, tourists still appreciate the remnants of its architecture and sophisticated hydro-engineering systems, composed of canals, moats and large reservoirs known as barays.

Researchers now studying sediments from one of the reservoirs report that prolonged droughts and overuse of the soil may have interfered with Angkor’s water management system and led to the empire’s decline.

“When Angkor collapsed, there was a drop in water levels,” said Mary Beth Day, an earth scientist at the University of Cambridge in England. “And much less sediment was delivered to the baray at the time.”

Angkor’s population may have been growing, and the soil may have been stressed from aggressive use, she said.

“The sediment being delivered to the reservoir during Angkor times was more weathered than the sediment being delivered post-collapse,” she said. “The land was used fairly aggressively for agriculture, as opposed to when people left.”

Ms. Day sampled six and a half feet of sediment core from Angkor that allowed her to study its physical properties, like the abundance of various elements and the ratio of sand to finer-grained materials.

She and her colleagues published their research in the current issue of The Proceedings of the National Academy of Sciences.