Recently, the outlying areas around Cambodia’s Angkor Wat have been subject to some remarkable discoveries thanks to the use of a pioneering new laser technique called LIDAR.
What is LIDAR?
Lidar is an airborne laser scanner (ALS) which is mounted to a helicopter and has recently been used for some incredible archaeological discoveries in Cambodia. The helicopter is controlled to fly on precise guidelines of altitude, airspeed and flight path. The ALS the scans the ground below with no less than 16 laser beams per square meter during the survey flights. The time it takes for the laser to rebound from the ground back to the receiver determines the topology from each individual data point below.
The data that is received is then calibrated and configured into a 3D model based on the information collected during the survey. The 3D model is then handed over to archaeologists who analyse it.
Once completed, the final 3D model is handed over to the archaeologists for analysis, which can take months to process into maps.
LIDAR Survey in Cambodia
The state of the art air mounted laser scanning technology has recently revealed to archaeologists that there is, in fact, many more vast temple structures and complexes hidden by Cambodia’s dense jungle.
The area that has already been subject to the laser survey is close to the ancient city of Angkor Wat. Even though this is the start of a planned series of laser surveys, it has shown there are actually several cities between 900 and 1,400 years old beneath the dense Cambodian forest. Some of these ancient cities are believed to be bigger than the current capital, Phnom Penh!
The most extensive survey was carried out in 2015 and due to the exciting findings more are planned in the next 3 years. In the 2015 study, the team covered 734 square miles and backs up the theory that the Khmer empire would have been by far the largest empire on Earth at its peak in the 12th century.
Damien Evans is the Principal Investigator at CALI (Cambodian Archaeological Lidar Initiative) who are based in Cambodia and run the surveys.
Mr Evans said: “We have entire cities discovered beneath the forest that no one knew … we uncovered only a part of Mahendraparvata on Phnom Kulen [in the 2012 survey] … this time we got the whole deal and it’s big, the size of Phnom Penh big.”
Damien Evans obtained a European Research Council (ERC) to fund the project. This was granted based on the success of his first lidar survey in Cambodia in 2012. This revealed several cities in the vicinity of Phnom Kulen but it was until 2015 when the full extent of the cities was discovered.
These are landmark findings as they show advanced irrigation systems and construction that was thought not to exist for hundreds of years later. This has now changed the way historians view the evolution and standing of the Khmer empire.
Evans said, “Our coverage of the post-Angkorian capitals also provides some fascinating new insights on the ‘collapse’ of Angkor,”. “There’s an idea that somehow the Thais invaded and everyone fled down south – that didn’t happen, there are no cities [revealed by the aerial survey] that they fled to. It calls into question the whole notion of an Angkorian collapse.”
Angkor Wat temple and the many surrounding satellite temples make up the Angkor Archaeological Park which is by far the country’s top tourist destination has long been a UNESCO world heritage site. With the new research, it is now considered the biggest urban settlement of the pre-industrial era, however, its demise remains something of a mystery to archaeologists.
Evans also points out that in addition to the large cities and temple complexes they have also found strange geometric patterns thought to be allotments or gardens. Archaeological experts now agree that this is the most extraordinary discovery in some years.
Professor Michael Coe, who is considered one of the respected experts in the Khmer empire and civilisation said: “I think that these airborne laser discoveries mark the greatest advance in the past 50 or even 100 years of our knowledge of Angkorian civilisation,”