In the Siem Reap Province of Cambodia lies a medieval city called Angkor, also known as Yaśodharapura (jeaʔ sao tʰeaʔ reaʔ boʔ raʔ), the capital of the Khmer Empire (9th century-15th century). The ruins of Angkor housed the famous Angkor Wat Temple, Angkor Thom, the Bayon Temple, and complex infrastructures including the grand water system that helped the rise of Angkor… and its fall. A study of the crumbling water system was posted on the website Science Advances called The demise of Angkor: Systemic vulnerability of urban infrastructure to climatic variations. It is explained that “Complex infrastructural networks provide critical services to cities but can be vulnerable to external stresses, including climatic variability” as here they are going to be referring to Angkor’s infrastructural network, specifically the water system.

The study explains how the monsoons and years of drought in the area caused erosion and sedimentation within the canals causing the flow of water to altered in different ways. They tested this idea with a series of computer simulations, which in turn had shown that the climate had caused such a high-flood magnitude that the canals could not handle the volume of water. “These results indicate that damage is most severe near upstream bifurcations, especially those areas that serve as the primary distribution forks for main inputs. The most robust regions are located downstream of points at which damaged paths recombine. This is because damage can represent either decreased or increased flow. If a depleted and flooded edge recombine at some downstream node, their respective perturbations cancel,” they stated.

They go on and state that their model had shown the damage of the water system was focused at the major distribution nodes closest to the flow source. For example, the Siem Reap canal of the water system was particularly damaged since it was near to its flow source, the Pouk River. The information, as the authors of the study conclude, shows that the water system, including the entirety of Angkor’s urban infrastructure, “was prone to cascading failure under the impact of high-amplitude but low-frequency climatic perturbation”. This played a role in the demise of Angkor. Also, it was concluded that the long droughts of the 13th and 14th century, and the abrupt transition of the water years in the middle of the 14th century caused the water canals to be unequilibrated (unbalanced) so they could not handle the large quantities of water from the monsoons, breaking them down by erosion and sedimentation.

The city of Angkor was abandoned at around the year of 1431 due to these problems alongside with other reasons of natural disasters (the mentioned flooding and droughts, disease, earthquakes, and inundations), the drastic changes of the state religion, and the war with the Ayutthaya Kingdom at the time. It is said in the Cambodian Chronicles that the King of Angkor and his fellow administration left to “Middle Period” cities to the southeast, near the modern capital of Phnom Penh as did many commoners except for places like the Angkor Wat. To this day, people are attracted to its medieval structures of the Cambodia, and its lasting history. Its original builder, Yasovarman I, had constructed this city in 889 with the intentions of it being the new seat of the Khmer Empire. It served this purpose well, but again the canals of the water system that flowed the city’s water failed the Angkorians in the long run, forcing them to leave after so much time was spent building the grand city.