Indravarman I Builds the Empire's First Great Reservoir at Hariharalaya
The Indratataka baray sets the template for Khmer water engineering
Quick facts
- King
- Indravarman I
- Capital
- Hariharalaya (Roluos)
- Reservoir
- Indratataka, 3.8 km by 800 m
- Capacity
- About 7.5 million cubic meters
What happened
Ruling from the capital of Hariharalaya, in what is now the Roluos area near Siem Reap, King Indravarman I launched an extensive building campaign that included temples, palaces, and one of the first large-scale hydrological systems in Khmer history, according to the National Library of Australia's account of the period. He built the Indratataka reservoir, a man-made lake roughly 3.8 kilometers long and 800 meters wide that could hold about 7.5 million cubic meters of water, comparable to three Olympic swimming pools. During the monsoon the reservoir collected excess rainfall; in the dry season, canals and sluices released the stored water to irrigate rice paddies around the capital.
Why it matters
The Indratataka was the largest reservoir built in the region up to that point and established the baray, a rectangular reservoir tied to a state temple, as the signature piece of Khmer civil engineering. Every later Angkorian capital, including Angkor itself, would be built around a version of this same water-storage system.
How we know
The reservoir's dimensions and dry-season/wet-season function are documented through archaeological survey of the still-visible earthen dykes at Roluos, combined with temple inscriptions from Indravarman I's reign describing his building program.
Sources
- National Library of Australia, Digital Classroom. Building Angkor · Reputable sourcelibrary.gov.au · The domain "library.gov.au" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- National Library of Australia, Digital Classroom. The rise of Angkor and the Khmer Empire · Reputable sourcelibrary.gov.au · The domain "library.gov.au" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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