Paper short abstract:

In this paper, we assess the strengths and weaknesses of the water management system of Koh Ker to better understand the role of water management in the sustainability of Khmer cities.

Paper long abstract:

Several studies have argued that the collapse of an unsustainable hydraulic network was a major factor in the abandonment of medieval Angkor (~9th to 15th centuries AD) as the capital of the Khmer civilisation. However, Angkor presents us with a great deal of uncertainty due to the spatial and temporal complexity of the archaeological remains. The Angkor-period city of Koh Ker, in contrast, provides the opportunity to study a medieval water management system whose structure and functioning can be discerned with relative clarity. Here we present the results of an investigation into the archaeological landscape of Koh Ker, including the use of airborne laser scanning (lidar). We argue that the system at Koh Ker was a hybrid one, combining elements of a 'highland system' of damming river valleys (as on Phnom Kulen) with elements of the classical 'lowland system' of reservoirs, canals and bunded fields (as at Angkor). We identify weaknesses in the engineered landscape that rendered the water management system unsustainable and ultimately led to the catastrophic failure of the system, possibly within a few decades . Finally, we assess the implications of these data for our understanding of the importance of water management systems for the sustainability of medieval Khmer cities.