Hydrology Made Sexy – A Detective Story

Hydrology Made Sexy – A Detective Story

Introduction

Angkor is an amazing place. You cannot fail to be impressed even stunned by the grandeur, detail and scale of the monuments. The true wonder of the Angkorian Empire and what it achieved has only started to dawn on me in the last few years. It was when the findings of the Lidar survey surfaced that I grasped the extent of what was one of the world’s greatest civilisations.

Lidar in layman terms emits an electromagnetic pulse i.e. a laser, that is strapped to a helicopter and fired as it passes over the ground to be surveyed. The reflected light is fed through the software that strips away the vegetation to show the topography and reveal previously unidentifiable structures.

The results are phenomenal! Phnom Kulen had a city on top. Angkor Thom was laid out in a grid of roads and canals framing wooden houses and their trapaeng or pools. There were thousands of temples not hundreds, and it was all made possible by the management of water in a climate where at the best of times 6 months of rain is followed by 6 months of drought.

I also began to realise that many of our cycle routes, hiking trails and even kayaking adventures followed these ancient waterways. I’d heard Roland Fletcher give fascinating talks at Amansara and on the banks of the West Baray. It wasn’t until Damian Evans (also from Sydney University) spoke to the guides that I knew he could tell us what we needed to understand Angkor.

The Water Connection

Boeung Ta Neue – our Secret Lake where we kayak, was an Angkorian reservoir formed by an extension of the North Wall of the East Baray, a much larger reservoir connected with the Angkorian cities of Ta Prohm and Angkor Thom. Boeung or lake Ta Neue caught the rain run off from the Kulen Hills to the North, which fed the Baray and in turn the conurbations of Angkor.

Kayaking on Lake Ta Neue

Nearby the corner of the East Baray, where we discovered a wall separating the Baray from Lake Ta Neue, is the 7 arched Spean Tor Bridge. Clearly visible by kayak from the water, we managed to reach it through the bush. We searched on the Baray side for a connection with Lake Ta Neue but none was to be seen. We couldn’t work out the purpose of the bridge though to be sure a thousand years ago it had one.

 

 

 

Spean Tor Bridge

The main water flow in and out of the East Baray was through Kral Romeas, a sluice built into the banks of the East Wall. Cycling and hiking through Phum Samre, the village that lines the walls I’d noticed large laterite stone blocks. Closer inspection revealed 1 large thick wall and 30 metres away another running parallel. These formed the sides of the sluice, the raised ground in front of us was a laterite weir. Kral Romeas acted over time as an inlet and outlet to the East Baray and may have been connected by another laterite wall running parallel with the East Bank, to Lake Ta Neue via the bridge Spean Tor.

An outlet has also been discovered opposite in the West Bank at the far end of the Baray, which provided water for the wooden houses between Angkor Thom and fed into the Ta Prohm moat. 7km long and 2km wide the Baray seems to have been a huge body of water to supply what appeared as a compact area of habitation but it would also have been used for irrigation.

Damian put this into context by working out that the 50 million litre3 in the West Baray reservoir of similar size to the East Baray, could provide irrigation for 5000 ha of rice, perhaps 10,000 tonnes for each crop. The rice fed a population of hundreds of thousands of priests, the aristocracy and merchants who lived in and around the ancient temple cities.

The West Baray at the end of the rainy season

It was also unlikely that the 3 great water reservoirs of the West, East and North Barays were in simultaneous use but acted as a safe-guard for times of drought and flood.

The scale of these man made hydraulics are unparalleled in human history and mind-boggling. To truly understand you have to think about the 3 spatial dimensions in combination with a 4th dimension – time, the chronology of the kings and climate. History seems to have been determined by the weather as the peaks in the empire, first during the reign of Suryavarman II in the 12th century and second under Jayavarman VII in the 13th century coincided with the peaks in rainfall we saw from the ancient records on Damian’s computer screen.

The ultimate decline of Angkor was also linked to periods of extreme drought followed by flood years, which washed away this finely tuned hydrological infrastruture  needed to supply water during the dry season and get rid of it during the flood. This is most clearly seen at Spean Thmor near Angkor Thom where the old bridge lies high up the banks of the Siem Reap River, which now runs meters below.

Prasat Tor (prasat meaning temple) and Troung Chruk (pigs temple) it’s ruined sister temple to the South lie between Lake Ta Neue and the East Baray next to an unexplained mystery, a 10 x 10 grid of a 100 mounds.

Prasat Tor and it’s 3 laterite towers

Similar grids have been found beside the River of a Thousand Linga’s, Kbal Spean at the West end of Phnom Kulen and Sambor Prei Kup near the modern day city of Kampong Thom, both associated with major water systems. No artifacts or remains have been unearthed to help solve the mystery of what the mounds are.

Walking across where the grids were revealed by Lidar, we spotted fragments of curved roof tiles in a papaya plantation that in an act of unintended vandalism, has been planted right over the mounds, which may help solve the mystery.

Most of what is known about Prasat Tor comes from a 4 sided stele (a stone pillar with carved enscriptions) discovered by the French in the 1930’s and now stored in The Angkor Centre for Conservation. The Sanskrit engravings were translated and available on line, which Damian translated for us in his office that morning. The stele had been installed by a Brahmin priest during the 13th century referring to the Great King Jayavarman VII. The inscription mentions the Ganges River in association with water, which may have had something to do with the Kral Romeas sluice and was the same as an inscription found at Phnom Dai temple to the North, also the site of another grid of mounds. The temple itself appears to predate the stele and may have been built at the same time as the 10th century East Baray.

Randomly cast on the ground around Prasat Tor were the now eroded but once richly carved blocks that adorned the structure including the stone crown that sat atop the central tower. Interestingly it had a hole in the middle, where a bronze finial in the form of a trident could have been positioned. Possibly removed at certain auspicious times of the year to bathe the Goddess Shiva sitting 15 meters below in sunlight.

Now set amongst brilliant green paddy fields in November, on the other side of Lake Ta Neue is Leak Neang Temple dated to the 10th century. A stele has recently been removed from the site to the Angkor Conservation but has yet to be translated.

 

Leak Neang with its single brick tower

The bricks themselves are another mystery as no kiln has ever been found. A theory speculates that the bricks were fired close to the temples then used in it’s construction. The apparent black scorching seen on the walls seemed to support this idea.

Not only was this masterly management of water used to supply The Angkorians and irrigate their crops, it was also conveyed the enormous amount of stone required to build the temples. Laterite is an iron rich clay that is soft and easy to dress into blocks when it comes out of the ground. On exposure to the sun it becomes very hard but relatively light making it ideal for the foundations but not the decoration as its pock-marked surface is not easily carved. The laterite quarries lay in the hills to the West. Dams collected water from streams, which was released into the Great North Channel that carried the stone blocks South to Angkor.

At the Eastern end of the Kulen escarpment were quarries that supplied sandstone, which was carved into the marvelous facades of the temples.

A channel ran from Beng Melea past the Temples of Banteay Ampil and Chau Srey Vibol to Prasat Batchum inside Angkor.   A path still connects these sites and makes for a great cycle ride with temple stops for sustenance heading East to the Tamarind Temple – Banteay Ampil.

We were beginning to get a handle on the Eastern end of the water connection, now it was time to explore the Western end. The Siem Reap River flows South from the Kulen Hills to the the city and then onto the Tonle Sap Great Lake but during Angkor it was diverted into the North East corner of the Angkor Thom Moat. History is being repeated as subsequent to the floods of 2011 the channels have been reopened and another dug in parallel on the North side of the moat as the river is diverted into the West Baray with the aim of stopping the floods in Siem Reap. The fact that now the town of Puok to the West floods instead is not part of the discussion – tourists don’t go there.

Angkor Thom was Jayavarman VII’s and his 2 wives, city. The largest of all the Angkorian Cities its wall’s 3km long enclose  9 km2, which is now mainly forest but once housed a thriving metropolis of wooden houses and their trapeang, surrounded by a grid of canals and roads as the Lidar survey revealed.

View over the moat from the walls at the S.E corner of Angkor Thom

The data was detailed enough to show the individual houses, which can be extrapolated to give a guessed population of 70,000 based on an assumed family size. This would need a lot of water but during the rainy season any excess flowed out of Boeung Thom reservoir in the South West of the city and through Runta Dev a canal that runs under the city walls into the Angkor Thom moat. We’ve got a stunning cycle route that runs along the 8m high walls of Angkor Thom to Prasat Chrung or corner temple – there’s one at each corner. A great late afternoon spot for watching the sun set over the moat, paddy fields and palm trees beyond. We didn’t realise the engineering marvel that lay 8m below us until Damian lead us down the inner banks to a stream that on closer inspection disappeared into a laterite tunnel under the walls and out to the glinting light of the moat 30m away.

The West Baray 500m to the West is one more mystery. How was this vast body of water replenished and released during times of flood? The current outlet of the Angkor Thom moat is a canal running parallel with the road through the West Gate dug by the French, which destroyed any trace of what was there before. It is possible it was a replacement otherwise how did 50 million litres of water get into The Baray.

 

Runta Dev runs under the walls of Angkor Thom

What had we learnt that morning?

We understood that water running off the Kulen Hills to the North fed streams, which flowed into the reservoir / lake of Beoung Ta Neue in turn feeding the East Baray, which was a water supply for the population of Angkor Thom and Ta Prohm.

Damian confirmed that our cycling path to Chau Srei Vibol and on to Banteay Ampil, lay along the route a canal had taken bringing sandstone from the quarries at the Eastern end of the Kulen escarpment via Beng Melea to Angkor.

He explained how the laterite used to build the foundations of the J VII temples were carried by water released into the Great North canal which flowed to the North Baray and Preah Khan.

And the Western hydrological connection was made by the Siem Reap River coming from the Western end of Kulen flowing South into the Angkor Thom moat and maybe on into the West Baray.

And much else besides!

With great thanks to Damian Evans for a really fascinating morning and apologies for any misinterpretations.

Indochine Exploration with Smiling Albino Cambodia is pleased to take our guests on a introductory investigation of the main temples along the water courses described or an adventure to experience this incredible landscape on foot, by bicycle or kayaking.

The Story of Jayavarman VII as told by his temples

The Story of Jayavarman VII as told by his temples

JVII (Aka Jayavarman VII) with apologies to The Angkorian Empire                                       

It gets confusing, 26 kings all ending in – varman, building thousands of temples and ruling for 500 years. So today’s story is going to concentrate on just one JVII with references to his uncle SII, who was by all accounts also a very great king. And to set the scene we need to mention JII, who started it all on a mountain (so he could throw stones on the Cham who continued to be revolting throughout the Angkorian era).

Thevi I

JVII was born early 12th century into an empire at the peak of its powers. The nephew of SII, who ruled over the Angkorian Empire when it covered most of South East Asia including Champa – home of the revolting Chams – ‘boo’ (now Central Vietnam). As a teenager JVII was sent to Champa to learn it’s ways including military techniques, which as you’ll see comes in useful later in the story. It’s said that a Khmer allied Cham royal family adopted him. His first wife who we’ll call Thevi I, and figures early in the story traveled with him to Champa.

Meanwhile back in Angkor SII, while at the height of his reign was murdered by one of his commanders, who declared himself King. Word reached JVII in Cham that his uncle had been assassinated so he set off with Thevi I to exact revenge on the Usurper but he was too late.

The revolting Cham sensing a weakening of The Empire launched a fleet of boats, sailed up the Mekong and into The Tonle Sap Great Lake to invade, sack and kill the Usurper. JVII realized he wasn’t ready to attack the Cham so he headed into the forest to assemble an army.

Oh and in the mean time got the temple bug and built his first, Preah Khan in Kampong Svay, not to be confused with its namesake in Angkor (more on that later).

Preah Khan – Kampong Svei

Time was ticking and JVII getting on so at the age of 53, which was as long as a lot of Khmers lived for at the time. He marched at the head of his army to defeat the Chams. This was where those early years in Champa came in successful and after a campaign of 4 years they were defeated and he proclaimed himself King of The Angkorian Empire. Guess what he did first? Build a temple of course. Preah Khan, which while not a particularly original name was generally regarded as a very good temple. So good in fact that he dedicated it to his Dad and moved in. JVII was also regarded as a very good king, the best in fact and one reason was his secular approach to religion. A Buddhist but not an exclusive one he included Hindu’s in government and encouraged them to use his temples (probably so he could spy on them).

The 4 year campaign had taken its toll on Thevi I worrying about her love fighting those revolting Cham, she died of a broken heart. Bereft of the younger sister JVII married the elder, who we’ll call Thevi II and with her support embarked on his first phase of construction. Mindful of Chams and Khmers who wanted their old Hindu religion back he needed an Angkorian broad band. In those days roads were the only way to control a rather large empire so he built a lot of them with rest houses every 15km.

 Back or South Gate of Preah Khan – Angkor

His brand of Buddhism was unusually kind for the time and espoused being nice to each other so he built 102 hospitals. Reservoirs, he loved building reservoirs and dams and channels to connect them. That’s a story in itself but as part of all this Mahayana Buddhist niceness, it meant that his people could grow a lot of rice with irrigated water from his channels. In this part of the world, where there’s rice there’s fish so he ensured Angkor’s food security. In turn the population, honed, toned and hunky with JVII’s obsessive temple building, were ready to take on revolting Chams.

Thevi II, you remember her? Actually it wasn’t so long ago that they had married – was a big cheese in The Empire, Director of The Buddhist University and responsible for the morality of the kingdom.

Thevi II

Ta Prohm

Flush with success from all this building for the people he got back to temples for himself and started his second phase of construction, commissioning Ta Prohm for his Mum. JVII must have dreamt of temples because he was churning them out. Culminating in the third phase of construction and his masterpiece the Bayon. It was modestly dedicated to him. Depicting Mt Mehru at the center of the Universe AKA Angkor Thom, the state temple while he was alive and his tomb when he died.

In the 13th century this was a city of 70,000 people living in a Florida style grid of villas each with their own pool and 2 Oxcart parking lots. Location, location, location JVII had the best, his wooden palace with of course a pool and for him elephant parking, looked out over The Bayon. The omnipresent loksvara, mugshots of himself carved into the stone pillars reminded those upity Hindu’s who was boss.

Loksvara said to be in the likeness of JVII

Old JVII, he was old by now probably around 70 when construction on Angkor Thom was started, had had a monumental life, certainly he left a lot of them. And must have wanted to record his achievements especially when if came to fond memories of bashing the Chams.

Unlike most Khmers today he didn’t have a smart phone so the next best thing was to commission an army of sculptures to carve out a comic relief on the walls of his state temple. Like the Terracotta Army in 2D great battle scenes are enacted, daily life depicted and the wonderful diversity of the Cambodian countryside recorded.

 

Above The Bayon and below a scene from the South East outer wall depicting the sacrifice of a water buffalo (another proof if need be of JVII’s regard for his people in that he stopped sacrificing them)

 

A great king not Mohammed, Jesus or Buddha himself but hey when you’ve reached your nineties and all your mates died 30 years ago perhaps not surprising JVII might have been thinking along those lines. These delusions of grandeur expressed in the construction of Angkor Thom a 9km square city, were beginning to sow the seeds for the subsequent decline of Angkor. The reservoirs and canals that had allowed hundreds of thousands of people to live in an infertile sand pit were not maintained and not prepared for the great drought and floods that followed his death. The system of water management was washed away and the city was no longer able to feed itself, but we’re getting ahead of our story. In the meantime his death; rumors abound, was it Hindu extremists, a jealous son, an estranged wife? At 95 years old it was probably old age.

The dates vary according to which account you read but all are remarkable for the time. 1125 seems to be a probable birth date and 1220 his death. He was crowned in 1181 at 56 and ruled for 39 years during which time Angkor became the greatest empire in the world, truly a great king.

Post script; JVII was succeeded by one of his surviving sons, we’ll call I (as in aye) 2, a leper who atoned for his sins by embellishing his Dad’s temples. JVIII is remembered as a religious vandal who spent most of his time knocking the heads off the Buddha’s that graced JVII’s temples.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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