SOCIETY × TECHNOLOGY

Angkor, City of Water

~1150 CE

History · Middle Ages · Holocene · Meghalayan

Angkor was one of the most extensive low-density cities of the pre-industrial world. Temples stood at the core; around them, revealed by airborne laser scanning, lay a settlement spread thin across the countryside, its house mounds, fields and canals, two reservoirs of some fifteen square kilometres each and more than three thousand household ponds. The whole fabric was a water machine. Modelling that network shows how the erratic monsoons of the fourteenth century could tear it apart: flooding damaged channels, the damage spread through the links between them, and failure ran on in cascade.

Why it matters

Angkor is where the vulnerability of infrastructure itself has been documented precisely for the first time in an ancient city: not just the crops or the armies, but the network, whose interdependencies could turn local damage into general failure, a mechanism its modellers compare directly to modern critical infrastructure. And the airborne laser scanning that drew the invisible city out of the forest has changed what archaeologists expect to find under a canopy.

Dating & uncertainty

Angkor was the Khmer capital region from the ninth into the fourteenth century; the date shown here is its twelfth-century height, the age of Angkor Wat. The demise is the debated part: network modelling shows the water system prone to cascading failure under the fourteenth century's swings of drought and deluge, while remote sensing argues that political unrest was already reshaping the city before the worst of the weather.

Sources

1. Penny et al. (2018), Science Advances · The demise of Angkor: systemic vulnerability of urban infrastructure to climatic variationsdoi:10.1126/sciadv.aau4029
2. Hanus & Evans (2016), Archaeological Prospection · Imaging the waters of Angkor: a method for semi-automated pond extraction from LiDAR datadoi:10.1002/arp.1530
3. Klassen et al. (2021), Remote Sensing · Deciphering a timeline of demise at medieval Angkor, Cambodia using remote sensingdoi:10.3390/rs13112094

Our species’ history as one day

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if the 315,000 years of Homo sapiens were compressed into a single day