AWARD OF EXCELLENCE / SPECIAL PROJECTS Rewriting the History of the Khmer Empire

Juror Comments:  “By taking a Canadian engineering tool and using it outside the normal applications, this innovative project helped to unearth ancient temples and settlements in Southeast Asia.”

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For 150 years, archaeologists in Cambodia have been researching the Khmer Empire that dominated Southeast Asia 1,000 years ago and left behind spectacular temples such as Angkor Wat.

Vancouver-based McElhanney introduced new LiDAR mapping technology to the archaeologists and was instrumental in a massive data collection project in Siem Reap and Preah Vihear Provinces in northwestern Cambodia. The project has resulted in the discovery of 29 new temple sites and extensive urban development that was formerly obscured by forest. As a result, the history of the Khmer Empire is now being rewritten.

Light through the jungle

Much of the exploration and research undertaken over the past 150 years in and around Angkor has been carried out by ground survey. More recently, aerial photography and radar surveys added to the information available. However, the dense forest cover, decades of civil unrest, and the resulting presence of landmines and unexploded ordnance have combined to severely limit the ability of archaeologists to fully explore the extent of the Khmer Empire’s urban and agricultural development.

Using LiDAR, McElhanney helped substantially overcome these difficulties. Unlike other mapping techniques, airborne LiDAR technology uses light pulse emissions reflected by the ground. The technology works by measuring the time lapse between transmission and return of the light pulses to establish subtle ground forms with unprecedented accuracy.

McElhanney has pioneered the use of LiDAR since its inception in the 1980s, but only in recent years has the technology become sophisticated enough to generate millions of ground elevation points per square kilometre, even through heavy vegetation.

Since 2002, McElhanney has been involved in projects in Cambodia, and recently became aware of the difficulties facing archaeological teams working in the region. After being inspired by the experimental use of LiDAR for archaeological research at the Stonehenge World Heritage Site in England and the ancient Maya city of Caracol, Belize, McElhanney persuaded Dr. Damian Evans, deputy director of the Greater Angkor Project, of the technology’s potential.

With McElhanney playing a coordinating role, eight archaeological research organizations from around the world formed the Khmer Archaeology LiDAR Consortium, headed by Dr. Evans, to raise funds for the project and share the resulting data.

Billions of data points

McElhanney designed a gridded flight plan, customized to the site, to produce ground elevations at a high density and accuracy.

LiDAR data collection is usually carried out from a small plane, but the point density requirements and weather dictated using a helicopter. McElhanney designed a custom pod to house the LiDAR system, which was then mounted on the port skid of the only suitable helicopter available locally, a Eurocopter AS350B3+.

The results of the data collection were even better than predicted, yielding billions of data points at an average density of 12-14 points per square metre, complemented by approximately 5,000 high-resolution digital aerial photographs.

The data collected will take many years to analyze but has already revealed the existence of more than two dozen previously unknown temple sites, as well as evidence of inhabitation and agriculture extending far beyond previous estimates.

As an example, the mapping of the forested enclosure of Ta Prohm revealed in the words of Dr. Evans, “an entire ancient city beneath the forest, with a precisely laid out grid of streets, canals, ponds and occupation mounds, which no one had ever noticed in spite of 150 years of research and 2 million tourists per year.”

In the short term, the new discoveries will attract additional tourism and scientific exploration to Cambodia. In the long term, the survey will improve our understanding of how the Khmers managed water, which is believed to be a key factor in why their Empire rose and eventually fell.

Covering 270 square kilometres and completed on time and on budget in 2012, this was the largest archaeological mapping project ever undertaken. cce

Project name:

Rewriting the History
of the Khmer Empire

Owner/client:

Khmer Archaeology
LiDAR Consortium

Award-winning firm/prime consultant:

McElhanney Consulting Services,
B.C. & Indonesia (Chris Newcomb, P.Eng.; Jim Christie; Francisco Gonçalves; Chris Cromarty; Oliver Swaffield; Glorie Siahaan; Imam Hartono; Primaristianti Putri)

Other key players:

Helistar Cambodia
(helicopter owner-operator)