Angkor – What Ancient Water Infrastructure Can Teach Us Today

The pre-industrial city of Angkor in Southern Cambodia, most famous for the ruins of Angkor Wat today – with its heyday in the 13th century, had a very complex water infrastructure system.

The features of this system included and were not limited to man-made lakes as reservoirs, canals, moats, and embankments.

The main purposes for this water distribution network were flood control and irrigation and it covered a vast area (1200 square kilometers, give or take).

Seemingly the city of Angkor’s collapse and the neglect of maintenance for this infrastructure coincide, and it has been suggested that water-related issues contributed highly to the aforementioned event. Science Advances reports:

“We conclude that Angkor’s urban infrastructure, particularly its very large and convoluted water distribution network, was prone to cascading failure under the impact of high-amplitude but low-frequency climatic perturbation. This critical behavior was likely to have been the product of centuries of iterative development of water management infrastructure, creating a system that was at once very large, tightly interdependent, and characterized by the reuse of older, redundant infrastructure. It follows that earlier, less extensive, or interdependent phases of the same network may demonstrate different characteristics in terms of topological damage in response to climate forcing, and may have been more resilient than the network as we model it, at the peak of its complexity in the 14th century CE.

The abrupt transition, in the middle of the 14th century CE, from prolonged drought to particularly wet years, meant that the network was disequilibrated with prevailing weather. The subsequent adjustment of the system, through erosion of the major offtakes and centralization of flow, exploited the systemic vulnerability shown by our model and resulted in probable breakdown of the network.

There are two primary outcomes of this finding. First, the basic pathology of Angkor’s collapse is analogous to the challenges faced by networked urban infrastructures in the modern world. This was not an exotic catastrophe with no modern analog, nor was it the result of unique exogenous forces. Second, this historic example of the cascading failure of critical infrastructure as a result of climate extremes reemphasizes the importance of building resilience into modern networks, resilience engendered through modularity and redundancy, to cope with high-amplitude/low-frequency climatic extremes, of which we may, at present, have no historical or instrumental precedent.”

Looking to history for infrastructure insight is hardly a foreign concept – most modern infrastructure is based off Roman models, and those are more than a thousand years older than Angkor’s.

What can be learned from Angkor’s successes and failures may be extremely valuable as infrastructure management experts move into the realm of climate-related upgrades to existing systems, to achieve required infrastructure resilience outcomes.