Monsoon-driven flooding weakened the water infrastructural network of Angkor, likely leading to the fall of this urban infrastructural network – the largest of the preindustrial world – according to a new analysis*. The findings may help experts better understand the vulnerabilities of modern infrastructural networks in urban environments where high-impact, low-frequency weather events pose a threat, say the study’s authors. The multifaceted infrastructural networks seen in cities provide critical services to many people around the world. According to Dan Penny and colleagues, the study of the stability of preindustrial urban networks stressed by climatic variation can provide important insights into the stability of such networks over long periods of time. Here, Penny et al. analyzed the topology of the ancient city of Angkor, one of the world’s most extensive cities by the 13th century CE. It featured canals, moats and reservoirs used to acquire, store and distribute water resources, as well as to regulate flooding. The authors investigated the ancient city’s topological vulnerability to erosion and sedimentation as caused by variations in rainfall conditions. After modeling the city’s infrastructure network based on archeological remote sensing and mapping, the researchers applied a numerical simulation model of erosion and sedimentation within the water network to determine whether the processes could change how water traveled through the network. They found that very large floods would result in systematic instability of the water distribution network, with the damage more severe near important upstream junctions. Extreme rainfall occurred in mainland Southeast Asia during the final decades of the 14th century and likely forced the network into a sudden unstable phase that contributed to the fragmentation of Angkor’s infrastructure network at that time, Penny et al. say.

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Article Source: A Science Advances news release. Science Advances is a publication of the AAAS (American Association for the Advancement of Science)

*“The demise of Angkor: Systemic vulnerability of urban infrastructure to climatic variations,” by D. Penny; C. Zachreson; R. Fletcher; D. Lau; J. Lizier; N. Fischer; M. Prokopenko at University of Sydney in Sydney, NSW, Australia; D. Evans; C. Pottier at École Française d’Extrême-Orient in Paris, France.