Khmer Hydraulic Irrigation System

Timeline

1. c. 800–1000Northern edge of the Tonlé Sap · CambodiaEarly Khmer monarchs excavated barays and diversion channels at Roluos and in the Angkor region, using the seasonal rise and fall of the Tonlé Sap to regulate irrigation and laying the agricultural foundation for the capital's expansion.
2. c. 1180–1220Angkor Thom and the West Baray · AngkorJayavarman VII expanded giant reservoirs such as the West Baray and linked them with the city's canal network, supporting the food and ritual water needs of a capital of up to a million people and its temple complexes.
3. 1401–1410Angkor site area · AngkorBetween 1401 and 1410 the Khmer political center had shifted south; the Angkor barays and main canals silted up for lack of maintenance, and only some areas still supplied small-scale rice cultivation and monastic communities.
4. c. 1431–1900Angkor and the Siem Reap plain · CambodiaAfter the Siamese captured Angkor in 1431 the hydraulic system ceased functioning entirely and was swallowed by the jungle; French archaeological and remote-sensing research in the 19th–20th centuries revealed its scale, making it key evidence for understanding Khmer civilization.