Water Efficiency

Climate Change and System Complexity

Resilience lessons from an ancient civilization

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Angkor, Cambodia, was one of the world’s foremost cities in the 13th century. The ancient urbanization extended across more than 1,000 kilometers and boasted an elaborate water infrastructure network—a system of reservoirs, embankments, and canals that irrigated farmland, diffused floodwaters, and distributed water among residents.

In the 15th century, however, the city collapsed, and its inhabitants moved elsewhere. Experts have long speculated about the reasons for Angkor’s demise. A recent study indicates that the vulnerabilities of the infrastructure network, paired with climatological factors, may have contributed.

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A team of experts from the University of Sydney recently used archeological data to create mathematical models of Angkor’s system that allowed them to quantify infrastructure damage caused by variations in climate. Their work is published in Science Advances. The model revealed that damage to infrastructure caused by flooding likely contributed significantly to the city’s ultimate collapse.

Complex networks have proven vulnerable to cascading failure when one issue results in a series of system-wide complications, researchers explain. Their model of Angkor’s intricate network was made up of 1013 edges and 617 nodes. It helped them determine that infrastructure damage was most severe in areas that served as primary hubs, according to Ars Technica, which most likely led to a number of downstream failures.

“The water management infrastructure of Angkor had been developed over centuries, becoming very large, tightly interconnected, and dependent on older and aging components,” co-author Mikhail Prokopenko, director of the Complex Systems Research Group at the University of Sydney, said in a press release. “The change in the middle of the 14th century CE, from prolonged drought to particularly wet years, put too much stress on this complex network, making the water distribution unstable.”

Today’s cities are highly complex and are also connected by aging infrastructure, making them increasingly vulnerable to the effects of extreme weather events and climate change. In fact, the factors contributing to Angkor’s water network failure may parallel challenges faced by modern urban communities struggling with complex critical infrastructure.

What are your impressions? What can we learn about ensuring system resilience from Angkor’s experience?

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  1. The problem lies not just with the aging infrastructure, but also how we as the users perceive it. We expect a level of service continually and resists, sometimes strenuously, the need to change behaviours around use. This is no doubt what happened around Angkor as well. Locals continued to expect the same level of service with little adaptation to changing availability. Why do we expect water to always be on tap? Why does grey water always have to flush away? If we change our behaviours, we reduce pressure on aging networks, reduce costs and allow time and funding for repair.

  2. I strongly agree with commenter, Yvonne. In fact, this is the current issue at the heart of all our (natural) resource concerns. Teaching geography at the community college level, I can’t help but inform my students of the paradigm shift we MUST make over the next decade–NOT decades–to ensure the capacity of biospheric systems to support life as we know it. Alas, they’re an easy audience. The real buy-in needs to occur among and across the greater human population. That’s supposed to be promoted and championed by political leadership. Yet the individuals in these positions (at the extreme ends on both sides of the political spectrum) continue to sell us out. The vast majority of the scientific literature reads that we’re running out time to make the serious decisions and take the actions that must be made. What is it in the code of our DNA that disables us from reconciling with the realities that loom on the horizon of our very existence? Must we always be a reactionary, instead of a proactive, species? Indeed, the answers and viable alternatives have arrived and can be scaled to meet the requirements of our 7.5 billion and growing population. But our elected leadership is effete. Truly, if we don’t change our minds and actions from pessimistic denial toward the practice of possibilism, we’re a doomed species. And, in fact, if that’s the case, then we simply won’t persist into the future since we apparently don’t have the will to adapt and change.

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