From the 5th century CE onwards the Khmer world began to create a variety of water management systems. Out of these developed the baray, a unique form of reservoir utilising water held entirely or substantially on the existing ground surface by substantial surrounding banks. While the sequence of development of the baray is still partially obscure it is clear that this form of water management and its associated networks of channels predates the late 9th century formation of Angkor and may predate it by several centuries. The significance of the period when the baray came into being is that this form of reservoir may have come into use in a relatively dry environmental water regime and then became profoundly significant first as a manager of erratic water supplies in the initial unstable climate changes of the Medieval Warm Period, becoming a stabiliser and risk management system for ensuring crop production from the 9th to the 13th century. The baray and their networks were therefore a pre-adaptation which secured crop supplies in an uncertain period and then supported increased aggregate crop yields in the peak warm phases of the Medieval Warm Period. The baray may therefore be usefully envisaged as a pre-adaptation which sustained the initial endurance and expansion of the Angkorian state and then stabilised its capital up to the 13th century. Some of the water infrastructure became immensely large. The massive material inertia that had been built into the baray and their canal networks then interacted with a new phase of extreme climatic instability in the 14th and 15th century. Planetary cooling in the late Medieval Warm Period produced monsoon intensities beyond the operational parameters of the network. In consequence the inertia of the network contributed to the disruption of a remarkably and uniquely elegant, simple and sophisticated water management system in Greater Angkor, leading to the demise of the capital in a period of great social and political transformation between the 13th and the 16th century CE.

从公元5世纪开始，高棉世界开始建立各种各样的水管理系统。在这些发达的巴莱外，一种独特的蓄水库利用周边现有的堤岸形成并占据了大量的地表空间。虽然巴莱的发展序列仍然有些模糊，但很明显，这种形式的水管理和相关的渠道网络应当早于公元9世纪晚期吴哥文明形成之前，或者可能在更早的几个世纪之前。巴莱形成时间的重要意义在于，它投入使用是在一个相对干燥的环境之中，之后在中世纪暖气的不稳定气候变化中，水的供应也变得不稳定，而巴莱则成为了一个重要的调节管理措施，它确保了从公元9到13世纪谷物的生产。因此巴莱和相关的网络系统作为一种预调节手段在不稳定的时期确保谷物供应，并在之后中世纪温暖期最温暖的阶段极大的增加了谷物的产量。同时巴莱也为吴哥国家的最初的维持和扩张提供了预先的条件，且之后直到13世纪还帮助稳定着国家的首都。一些有关水的基础设施逐渐变得大型化。而这种大型化的惰性则与公元14和15世纪的极端不稳定气候有所互动。在中世纪温暖期后期，行星冷却产生的季风强度超出了这个沟渠网络所运行的参数条件。最终，这种沟渠网络的惰性导致了大吴哥显著而优雅、简单而负责的水管理系统的中断，从而导致了一个伟大社会一段时间的终止和公元13到16世纪间政治的转变。

Dr. Roland Fletcher is professor of theoretical and world archaeology at the University of Sydney. Over the past thirty years Professor Roland Fletcher has developed a global and interdisciplinary perspective in archaeology, that integrates research, teaching and service. His fields of expertise are the theory and philosophy of archaeology, the study of settlement growth and decline and the analysis of large-scale cultural phenomena over time. In 1995 Fletcher published The Limits of Settlement Growth: a theoretical outline – an analysis of the past 15,000 years of settlement-growth and decline – with Cambridge University Press. He has an international reputation as a radical theorist and as the instigator of the Greater Angkor Project, which derives from his theoretical work and is part of a major research program in Cambodia. This program of research on Angkor has developed international collaborations for the University of Sydney and has enhanced its public profile through media presentations, such as the National Geographic International TV program ‘Lost City’. The Angkor research team also serves the intentional community through the applied research of the Living with Heritage Project at Angkor, in collaboration with the Cambodian government and UNESCO.