Angkor's temples and climate change doom

Wednesday, July 01, 2009
By Sen Lam
Radio Australia

The ancient civilisation based at Angkor in Cambodia collapsed in the late 16th century because of problems with a very modern ring to them, research by an international team indicates.

The Greater Angkor Project, based in Sydney, is preparing a paper arguing that extreme climate change and the failure of Angkor's complicated water systems were to blame.

The temple complex was the heart of the mighty Khmer empire and its ruins are one of the most popular attractions in South-East Asia.

The Angkor Wat temple, the centrepiece, was built in the ninth century and surrounded by huge reservoirs and canals - believed to be partly Hindu symbols and partly for irrigation.

Sydney archaeologist Professor Roland Fletcher, co-director of the team of scientists from France, Cambodia and Australia on the project, told Radio Australia's Connect Asia program: "It was actually the largest low density pre-industrial city on earth."

"It covers nearly 1,000 square kilometres, but that's all spread out, something like modern Los Angeles.

"So it was really enormous and it had somewhere in the order of, at the top end, 750,000 people in it."

Among the challenges for the authorities of Angkor were to manage the South East Asian monsoon and then a long dry season - that is, flood control and water delivery.

Professor Fletcher says this involved a massive water system, with canals as long as 40 kilometres, which "appears to have been the mechanism for holding water and using it as reserve in case monsoons were bad".

But from 1350 to 1500 AD, the region was hit by a very unstable climate, with droughts and severe monsoons mixed up.

Are there lessons from that period for modern cities?

"I would suspect there are, in the sense that what you see in Angkor is a landscape that has been completely cleared of forests in order to grow a dominant crop, so basically . . . simplification of the landscape and removing the tree cover," he said.

"On the other hand, [there is] the dependency on very big infrastructure for managing daily life - so, for instance, if you have really heavy monsoons that these canals and systems weren't designed to deal with."

"With severe monsoons, you would get severe damage to the structures, and we actually find that there is a dam up in the north that's been torn away and the big southern canals of Angkor are full of sand, which suggest very severe flooding."

For modern observers, "the situation is not absolutely equivalent - one reason being that we know a great deal more in the modern world, and we have a great deal more capacity available to us to deal with situations".

"But when you consider that Angkor was a giant low-density city, that had cleared its regional landscape of its natural vegetation cover, was dependent upon massive infrastructure and hit by climate change, it does sound a little topical.

"It does sound a little like the modern world."

The errors of Angkor

June 25, 2009
The Australian

But planners are not making the same mistakes, except in NSW

EXPLAINING one of history's great mysteries, University of Sydney archeologists, reported in The Australian yesterday, say the ancient Cambodian city of Angkor collapsed because it grew too big and was overwhelmed by extreme weather. Its fate, they say, has implications for modern cities. Indeed it does, but not the ones that enemies of the great Australian backyard will claim. Rather than expanding, perhaps Angkor's problem was that it was run by ancient equivalents of the NSW state government. Angkor's administrators did not adapt their infrastructure to changing circumstances. They let their city expand but did not maintain services to support it.

Sound familiar? It will to anybody who lives in the northwestern suburbs of Sydney, where a repeatedly promised and much-needed suburban railway has not been built and the roads are utterly inadequate. But the damage done by official incompetence is not the message inner city activists will draw from Angkor's fate.

This sort of research is easily misused by deep green ideologues who dislike people because they believe our presence pollutes the natural environment, activists who use Jared Diamond's theory of what happened when the people of Easter Island over-used their resources as a metaphor for the modern world. Such arguments suggest we are doomed to repeat Angkor's experience, that we cannot repair infrastructure and do not know how to use engineering to address climate change, that we must not allow people to live where they like. Of course they are wrong ... apart, of course, from NSW.

Development pressures threaten Angkor Wat ruins

An aerial view over Banteay Srey temple, one of the many stone monuments built during the Angkorian period, in Siem Reap province, Cambodia, on Wednesday Jan. 23, 2008. (AP Photo/Heng Sinith)

Wed. Feb. 13 2008
The Associated Press

SIEM REAP, Cambodia -- By destroying vast tracts of forest to enlarge their farm land, inhabitants of the wondrous city of Angkor lit the fuse to an ecological time bomb that spelled doom for what was once the world's largest urban area.

So believe archeologists engaged in groundbreaking research into the ancient civilization of Angkor.

And they are warning that history could repeat itself through reckless, headlong pursuit of dollars from tourists flocking to see Angkor's fabled monuments.

"It's just a weird cycle. It seems like Angkor is self-repeating itself,'' said Mitch Hendrickson, who recently led an excavation as part of research into Angkor as a human settlement.

Conservationists have long expressed concerns about the state of the monuments, especially the stress from the tourist invasion. They also say the uncontrolled pumping of underground water to meet rising demand of hotels, guesthouses and residents in the adjoining town of Siem Reap may be destabilizing the earth beneath the centuries-old temples so much that they might sink and collapse.

"There's just so much building going on without any concern about the long term. Things are moving so fast in Siem Reap today that it's going to chew itself up very quickly and become unsustainable,'' said Hendrickson, an archeologist from the University of Sydney, Australia.

From their city, Angkorian kings ruled over most of Southeast Asia during their pinnacle between the ninth and 14th centuries, overseeing construction of architectural stone marvels, including Angkor Wat, regarded as a marvel of religious architecture.

While the 1431 invasion from what is now Thailand has long been regarded as a major cause of Angkor's fall, archeologists from the Australian university's Greater Angkor Project believe earlier ecological forces led to the city's demise.

Their findings supported a theory in the early 1950s by Bernard-Philippe Groslier, a prominent French archeologist, that the collapse of Angkor resulted from over-exploitation of the environment.

Angkor's inhabitants started rice farming from the low-lying area near the Tonle Sap lake just south of Siem Reap town, said Roland Fletcher, another archeologist with the project.

But gradually, they cut down natural forest to extend their farmland up to the slope of Kulen mountain, 80 kilometres to the north, said Fletcher, who led 10 archeologists to excavate various sites near the Angkor complex.

Flooding ensued, and huge amounts of sediment and sand were washed down to fill up canals -- thus probably choking the vital water management system.

Using NASA's airborne imaging radar data, the project has conducted numerous aerial and ground surveys across nearly 3,110 square kilometres which revealed that the city -- with about one million inhabitants -- was far larger than previously thought.

It covered some 1,000 square kilometres and featured a sophisticated hydraulic system that proved too vast to manage.

Angkor was "a huge low-density, dispersed urban complex'' comparable to Los Angeles and "by far the most extensive preindustrial city on the planet,'' Fletcher said.

Its water network included an artificial canal used for diverting water from a natural river about 25 kilometres north of Angkor, and two mammoth, man-made reservoirs known as the East and West Barays.

"They (people) probably didn't necessarily need any of this extra water ... because just a rain-fed rice agriculture is quite sufficient to feed a very substantial population,'' said Damian Evans, a project member.

One theory, he said, was that the Angkorian kings built the water system just "to demonstrate their power and their authority to rule.''

But he said only excavations and soil analysis could yield more clues.

"It's a process of going to those sites on the ground and looking for finer detailed information like the profiles of the canals underneath the ground and the types of sediment that lie within those canals,'' he said.

Armed with a printed digital map of the Angkor area, Evans and Fletcher toured an excavation site at the West Baray where archeologists dug trenches to seek traces of an ancient channel through the bank. They were trying to determine whether the channel really existed and could have served both as water inlet and outlet.

The reservoir is walled by four banks -- now covered with jungle -- each 12 metres high, 110 metres wide and about 20 kilometres in length. It can store up to almost 51 million cubic metres of water.

Fletcher called it "the single largest artifact and piece of engineering in the preindustrial world.''

"All of this work is aimed at understanding how the water management system of Angkor functioned ... and how it stopped working,'' he said, adding that forest clearance is "the current key piece of information'' about the ecological peril that caused Angkor to tumble.

Although past environmental problems were associated with deforestation, they also underline the menace the tourism boom is posing to the temples, the researchers say.

"The same types of things which we knew were problems of Angkor are essentially being repeated in our modern-day context in the Angkor area -- things like unsustainable use of water, massive overdevelopment without any consideration of the long-term effects,'' Evans said. "There's definitely lessons to be learned from what happened here before.''