With a good overview
The ancient temple complex of Angkor in Cambodia includes more structures and remains of a prehistoric civilization than previously thought. Modern radar technology allows insights into the structure of the plant, which cannot be seen from the ground. Archaeologists say Airborne Synthetic Aperture Radar (AIRSAR) images developed by NASA's Jet Propulsion Laboratory (JPL) are revolutionizing our idea of how the ancient city evolved.
Located in northern Cambodia, Angkor has several thousand temples spread over an area of more than 160 square kilometers. The more famous among them were built between 800 and 1300. A tremendous number of water reservoirs and canals accompany the buildings. Little is known about the settlement of the fertile floodplain, but at its peak the ancient settlement is estimated to have numbered one million people. Today, much of the city is hidden under a dense canopy of leaves and difficult to access by land due to poor roads, landmines and political instability.
"The radar images have enabled us to discover some circular cairns and as yet undescribed temples in north-west Angkor," says Elizabeth Moore of the University of London.
In December 1997, she examined a small cairn on the outskirts of Angkor Wat, a famous twelfth-century temple. "Previous archaeological surveys from 1904 and 1911 record only two temples and make no mention of the detached circular cairns. We have discovered four to six temple remains, including pre-Angkorian structures," says Moore."This suggests that this area was settled 300 years earlier, not in the twelfth century - a radical change in the previously accepted chronology of Angkor."
The beauty of Angkor is made up of the temples, but the actual size of the Khmer city is based on the many constructions to regulate the water balance. The kings officially dedicated the temples to Hindu and Buddhist deities, but the real purpose was to worship the ancient spirits and thus ensure the fertility of the soil. The water balance was of crucial importance for this. During the rainy season, the water masses of the monsoon had to be controlled and partly stored for the dry period. The system includes ditches, dams, canals, tanks and reservoirs, the largest of which dates from the twelfth century and is eight kilometers long.
"These new, highly detailed topographic maps have revealed many more hydrological features and their function in rites and daily life," explains Moore. With the help of radar interferometry, three-dimensional maps were even created that are more precise than some maps of the USA. From them, the scientists can recognize which regulatory mechanisms of the water balance are natural and which are of human origin. This gives them an insight into human intervention in the ecosystem - from the time of the ancient Khmer to the present.
You can find articles on radar interferometry in: Spektrum der Wissenschaft 9/1997, page 56 and 65
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