Radar imagery is shedding new light on Cambodia's "heart and soul" - the
Tonle Sap and Angkor. Keith W. Eirinberg attended a Florida conference last
month which took a high-tech look at Cambodia's history.
SCIENTISTS are beginning to piece together a new picture of the historic Angkor area
and the Tonle Sap great lake, with the help of radar images taken from the space
shuttle Endeavor, aircraft and satellites.
Among new theories are that Angkor was based around a tree-shaded ancient beach,
and that the western Baray was, in part, a huge animal pen for water buffalo or elephants.
Unlike the builders of many ancient cities in the West, Ankgor's architects did not
rip down large areas of vegetation to make way for their monuments, but built them
between trees. The "temple forest" that exists today is not merely the
result of untamed jungle closing in on ruins neglected over centuries.
The latest discoveries were revealed at the second scientific roundtable on the subject
"New technologies and global cultural resource management" held April 15-19
at the University of Florida, Gainesville. It was organized by two preservation groups,
the New York-based World Monuments Fund and the Royal Angkor Foundation in Hungary.
The symposium brought together specialists in archaeology, architecture, ecology,
history and other fields to meet with scientists from NASA's Jet Propulsion Laboratory.
In a Sept 1994 space mission, NASA's Endeavor took radar images of Cambodia - transmitting
harmless X-ray radiation and recording the rebounding waves - to produce detailed
data on the vegetation and terrain around Angkor and the Tonle Sap.
For the past 14 months, scientists have pored over the images, matching them to aerial
and satellite photographs and cartographic and topographical information.
The results were unveiled to roundtable participants including special guest Vann
Moulyvann, vice-president of Cambodia's Supreme Council of National Culture, who
expressed gratitude for "the enormous advance that this new technology gives
to us to rediscover our past."
In arid climates, radar, which requires no visible light, can penetrate desert sands,
highlighting long-extinct trails, underground streams and springs and buried ruins.
Hopes that the Endeavor images would highlight any buried remains of the Angkor empire
were scuttled because the moist soils of the area were not reflective enough.
Nevertheless, scientists said the radar produced valuable information for scientists
studying the hydrological features of Angkor and the Tonle Sap, particularly when
matched with other available data.
Radar data has enabled Terry Schnadelbach, Professor and Chair of Landscape Architecture
at the University of Florida, to develop a theory to explain why Angkor was built
at its particular site.
Comparing data from soil borings conducted by Japan's Sophia University with the
radar images, he determined that Angkor was built upon the site of an ancient beach,
with large sand deposits lying near the surface. The builders of Angkor probably
liked this area of higher ground with its distinct vegetation.
Radar images convinced Schnadelbach that Angkor's builders kept the already existing
tree cover, probably to provide shade, he suggested. Schnadelbach views Angkor as
distinct from ancient cities in the West, where large areas of vegetation were generally
cleared before building was started.
Contrary to widespread belief, the elevated area of Angkor's western Baray was not
formed by sedimentation, according to Sch-nadelbach. The radar data, matched with
satellite imagery and topographic information, clearly shows that the walls of the
baray were built to keep something besides water within the reservoir's boundaries.
Schnadelbach speculates that the elevated area of the baray served as an animal pen
for water buffalo or elephants.
Radar imagery is also providing fertile grounds for research into undiscovered ruins
dating centuries before the time of the Angkor empire.
Dr Elizabeth Moore, Professor of Art and Archaeology at the University of London's
School of Oriental and African Studies, has helped interpret the radar data to identify
68 prehistoric mounds in the Angkor area.
There are four main areas of prehistoric settlement at Angkor: two in the central
area, one is in the Roluos area southeast of Angkor, and the other to the west near
an ancient river bed.
The prehistoric features, previously unrevealed, will provide plenty of scope for
Meanwhile, Schnadelbach said the radar clearly showed the presence of a large alluvial
fan that stretches out below the Kulen hills, with earth and stream deposits spreading
toward the Tonle Sap.
The alluvial fan traverses Angkor, going directly through the western Baray, with
unique sinkhole patterns where pockets of water caused the land to collapse.
The radar also showed underground springs as water traveled through internal aquifers
on the way to the Tonle Sap. The ancient Khmers correctly understood this system,
diverting the streams and taking advantage of the springs.
Scientists hope that radar also has great potential to help the future, particularly
with regard to development plans involving the Tonle Sap.
Schnadelbach said he had already discovered new features in the lake's tributaries
near Angkor. At a time when plans to dam the tributaries are being considered, he
said that radar may offer greater understanding of the life-cycle of the unique lake
and its associated rivers and streams.
It may help Cambodia in its attempt to prepare the Tonle Sap to be listed as a bio-reserve
on UNESCO's World Heritage List.
NASA does not have funding for further radar research missions aboard the Endeavor,
but is due to operate an airborne radar system on missions in South-East Asia later
The World Monuments Fund is talking with the Cambodian government and NASA about
including an overflight of Angkor from a DC-8 jet. If that goes ahead, a computer-generated
three-dimensional topographic map of the Angkor area could be produced, opening up
a new wealth of opportunities for greater understanding of Cambodia, past and present.
(Keith W. Eirinberg is a Fellow in the Asian Studies Program at the Center for Strategic
and International Studies in Washington D.C.)