Uncovering archaeological landscapes at Angkor using lidar

Phnom Penh Lovea 0 km 200 N Recent archaeological investigations and technological applications have increased our appreciation of the intricacies of pre-Angkorian societal development. The results reveal a transformative period characterised by increasing socio-political complexity, exchange and technological transfer, differences in burial wealth, growing levels of conflict and variation in site morphology. Among the excavated Iron Age sites in Cambodia, Lovea, near the heart of Angkor, is well placed to provide a greater understanding of these changes in this region. Excavation and remote sensing confirm that the two moats surrounding Lovea are testimony to the early adoption of water-management strategies. These strategies grew in complexity, culminating in the vast network of canals, reservoirs and tanks that are the hallmarks of the hydraulic society of Angkor.

Proceedings of the National Academy of Sciences, 2007

The great medieval settlement of Angkor in Cambodia [9th-16th centuries Common Era (CE)] has for many years been understood as a ''hydraulic city,'' an urban complex defined, sustained, and ultimately overwhelmed by a complex water management network. Since the 1980s that view has been disputed, but the debate has remained unresolved because of insufficient data on the landscape beyond the great temples: the broader context of the monumental remains was only partially understood and had not been adequately mapped. Since the 1990s, French, Australian, and Cambodian teams have sought to address this empirical deficit through archaeological mapping projects by using traditional methods such as ground survey in conjunction with advanced radar remote-sensing applications in partnership with the National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL). Here we present a major outcome of that research: a comprehensive archaeological map of greater Angkor, covering nearly 3,000 km 2 , prepared by the Greater Angkor Project (GAP). The map reveals a vast, low-density settlement landscape integrated by an elaborate water management network covering >1,000 km 2 , the most extensive urban complex of the preindustrial world. It is now clear that anthropogenic changes to the landscape were both extensive and substantial enough to have created grave challenges to the long-term viability of the settlement.

2008

This paper will focus on the results of a joint international project (a partnership between the University of Sydney and the University of Venice) that develops and applies satellite remote sensing methodologies for finding and mapping unknown archaeological sites in the surroundings of Angkor, in Cambodia. Long famous for its temples, this World Heritage site is now increasingly recognized as a vast, low-density urban landscape. The project consists of using the spectral content of remotely sensed images to reveal the presence of buried sites and structures of the ancient Khmer landscape on the basis of the different spectral characteristics of the terrain and vegetation. By applying spectral analysis, the current research aims to scan vegetated and bare soil areas in order to clarify features that are ambiguous in existing maps and reveal features which would otherwise remain undetected

Antiquity, 2019

Remote Sensing and Digital Image Processing, 2011

For more than a decade the multinational (Australian, French, Cambodian) Greater Angkor Project has been investigating the rise and fall of medieval urbanism at Angkor, in Cambodia, using a diverse range of techniques, including extensive use of remotely ...

Remote Sensing, 2021

The Greater Angkor Region was the center of the Khmer Empire from the 9th until the 13th to the 14th centuries CE, when it entered a period of decline. Many studies have suggested that the decline of Angkor was precipitated by several factors, including severe monsoons, geopolitical shifts, and invasions. In this paper, we use light detection and ranging and ground penetrating radar to investigate the possible intersection of two of these existential threats in one feature: the North Bank Wall. Our results indicate that this feature was designed with dual functionality of extending the urban area’s defenses to the east of Angkor Thom while maintaining the existing infrastructure for the distribution and disposal of water. These findings suggest that the North Bank Wall was built before the severe droughts in the mid-13th century. The timing of the construction indicates that the perceived need for additional security—whether from internal factional disputes or external adversaries—predated the final adaptations to the hydraulic network during the unprecedented monsoon variability of the 14th century. These results indicate that perceived political unrest may have played a more important role in the decline of the site than previously known.

In the archaeological literature regional centers often receive far less attention than capital regions and the medieval Khmer Empire (ca. 9th to 15th centuries A.D.) is a classic case in point. At its height, the Khmer Empire stretched across much of mainland Southeast Asia, and it remains the most extensive dominion in the history of the region. To date, however, relatively little archaeological work has been completed outside of the capital of Angkor, and we have a limited understanding of the broader dynamics of the Empire. In this paper we begin to address this lacuna at the remote monumental complex of Preah Khan of Kompong Svay, the largest of all the Angkor-period regional centers. We describe the use of remote sensing and ground survey methods to produce the first comprehensive archaeological map of the site. The map data are used to evaluate conventional interpretations of the site as a major industrial complex, urban center and military outpost. The findings have implications for our understanding of early urbanism, industrial production and imperial expansion in the region.

Journal of Field Archaeology

We report the results of drone lidar survey at a high-elevation archaeological site in the Chachapoyas region of Peruvian Amazonia. Unlike traditional airborne remote sensing, drone lidar produces very high-density measurements at a wide range of scan angles by operating at low altitudes and slow flight speeds. These measurements can resolve near vertical surfaces and novel dimensions of variability in architectural datasets. We show in a case study at Kuelap that the number of detected structures almost exactly matches the number reported from previous ground level surveys, and we use these data to quantify the relative circularity and size frequency distribution of architectural structures. We demonstrate variability in domestic architecture that was obscured in previous models produced using low-resolution remote sensing. Spatial analysis of these attributes produces new hypotheses about the site's construction history and social organization.

Journal of Field Archaeology

The Khmer Empire (9th-15th centuries A.D.), centered on the Greater Angkor region, was the most extensive political entity in the history of mainland Southeast Asia. Stone temples constructed by Angkorian kings and elites were widely assumed to have been loci of ritual as well as habitation, though the latter has been poorly documented archaeologically. In this paper, we present the results of two field seasons of excavation at the temple site of Ta Prohm. Using LiDAR data to focus our excavations, we offer evidence for residential occupation within the temple enclosure from before the 11th century A.D. until the 14th century. A comparison with previous work exploring habitation areas within the Angkor Wat temple enclosure highlights similarities and differences between the two temples. We argue that temple habitation was a key component of the Angkorian urban system and that investigating this unique form of urbanism expands current comparative research on the diversity of ancient cities.

Proceedings of the National Academy of Sciences of the United States of America, 2019

Alternative models exist for the movement of large urban populations following the 15th-century CE abandonment of Angkor, Cambodia. One model emphasizes an urban diaspora following the implosion of state control in the capital related, in part, to hydroclimatic variability. An alternative model suggests a more complex picture and a gradual rather than catastrophic demographic movement. No decisive empirical data exist to distinguish between these two competing models. Here we show that the intensity of land use within the economic and administrative core of the city began to decline more than one century before the Ayutthayan invasion that conventionally marks the end of the Angkor Period. Using paleobotanical and stratigraphic data derived from radiometrically dated sediment cores extracted from the 12th-century walled city of Angkor Thom, we show that indicia for burning, forest disturbance, and soil erosion all decline as early as the first decades of the 14th century CE, and that the moat of Angkor Thom was no longer being maintained by the end of the 14th century. These data indicate a protracted decline in occupation within the economic and administrative core of the city, rather than an abrupt demographic collapse, suggesting the focus of power began to shift to urban centers outside of the capital during the 14th century. Angkor | collapse | Cambodia | archaeology