As is so often the case, however, the system became a prisoner of its own complexity. The original system of canals and reservoirs was tied, over time, to new spillways, plus a larger canal and related dam. These show signs of having seen significant stress, perhaps a reservoir going dry, all causing endless repairs to keep this rickety and vast system of waterworks operating.
The preceding was likely survivable, but a complex and coupled system was pushed over the edge. According to recent tree-ring data, the region was hit by repeated mega-droughts, from 1362 to 1392 and again from 1415 to 1440. There were severe droughts followed by mega-downpours, likely causing food stresses, and even wiping out big chunks of the Angkor waterworks — and ultimately the Khmers at Angkor themselves.
A great example of how complexity can lead to ruin due to improbable, and uncontrallble circumstances. Politicians need to take note — just adding laws without overhauling and simplifying them can lead to systemic failure.