Restoration of Angkor Hydraulic Network
Restoring ancient irrigation is one of the main challenges in the Angkor site. This is not only a concern for the conservation of the temples and the sustainable development of Angkor but also a challenge to maintain water balance in the entire Siem Reap area due to the rapid growth of the number of tourists and the population. The key solution needed to meet the needs of daily water use and to ensure the stability of temples built on sand foundations is to expand water storage capacity at key reservoirs in the Angkor site.
In order to implement the plan to expand water storage capacity to the highest level possible, the APSARA National Authority has scientifically analyzed the origin from the catchment basin on Kulen Mountain to the point where the water flows into Tonle Sap. None of the inscriptions of the Khmer Empire mention the issue of floods or droughts, and the Khmer people have not narrated through legends or memories from generation to generation about any natural disaster. From this, it can be concluded that these problems did not occur in the past because the ancient irrigation management system was able to control the water very well. This conclusion is based on a natural and scientific examination of the water flow and the general interconnection between the irrigation system in the Angkor site, including the waterways along the Puok River in the west, the Siem Reap River in the central part, and the Rolous River in the East of the baray, moats, streams, pools, and canals. On closer inspection, Puok River and Rolous River are naturally occurring rivers, while the Siem Reap River appears to be an artificial waterway as it was created to divert water from Phnom Kulen with a stone dike construction that was built in the 9th century in the Bompenh Reach village, which is 60 meters wide and 300 meters long.
In the next step, the APSARA National Authority spent eight years conducting practical research on the ancient irrigation system. The study period showed that the northeastern part of the northern baray had a dam built from east to west and an ancient stone bridge made of laterite with many drainage barriers built on Siem Reap River that can be used for water flow and control. Due to these interconnected systems and streams, the diversion of water to the west (northern baray, western baray, and Puok River) to the east (Rolous River) and south (Angkor Thom’s moat, Angkor Wat,’s moat, and Siem Reap River) can be done smoothly without any obstacles.
Through the analysis of preliminary data and scientific conclusions of the floods of 2009, 2010, and 2011, the APSARA National Authority has carried out a number of necessary practical tasks, such as repairing and restoring the ancient Angkor irrigation system. Especially in 2012, a significant part of the ancient Angkor irrigation system was restored, which prevented the Angkor site and the entire city of Siem Reap from being flooded. This clearly indicates that the ancient Angkor irrigation system not only managed the water resources well but also managed the floods.