History Lesson: You're Only as Good as Your Water Supply

Famous civilizations, such as the Mayans and the Mesopotamians, have crumbled from apparently overusing their local water supplies. Researchers this week added another civilization to that list, as reported by 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.

This is, of course, a Malthusian-style reminder that it is indeed possible for a population to grow beyond its resources. It may not always happen everywhere, but it can and has happened.