Around the 10th century, the largest irrigation project in the history of the Khmer Empire was built in Koh Ker, northern Cambodia today.

The project failed after only the first year of operation and the king was forced to leave the capital for Angkor Wat.

koh ker

The event of the king leaving the capital to return to Angkor Wat has attracted a lot of attention from scholars and researchers. Dr. Ian Moffat, from Flinders University, led a team of international researchers who went to the Koh Ker area to survey to find the cause of the incident. They used ground-penetrating radar to map this area at that time.

According to Dr Moffat: “At that time, the implementation of civil engineering projects such as temples, urban renewal and water infrastructure development were central to establishing the legitimacy of the Khmer kings”.

According to a study published in Geoarchaeology, archaeologists discovered an irrigation project with a 7km long embankment designed to collect water from the Rongea River. But it can only hold average water flow.

Map of the area of ​​Koh Ker showing the location of the spillway and important archaeological features. It also shows the location of Koh Ker relative to Angkor, Phnom Penh and Ho Chi Minh City in the bottom right photo. (Photo: Flinders University)

The embankment could not withstand the large amount of water during the first rainy season. This calls into question the legitimacy of the Khmer king who ordered the construction of the irrigation works.

Dr Moffat said: “It is not difficult to predict that the failure of the embankment at Koh Ker – the largest and most ambitious infrastructure project of the era – had a significant impact on the king’s reputation. This therefore contributed to the decision to reestablish Angkor as the capital of the Khmer Empire.”

Koh Ker is located 90 km northeast of the capital Angkor. There are still many mysteries in this area even though it was the capital in the mid-10th century under King Jayavarman IV.

The site is located in a gently sloping hill and rocky mountains, far from the Khmer heartland – the flood plains.

Co-authored Leaksmy Kong with field assistants in Cambodia. (Photo: Flinders University)