Natural Landscape of the Vat Phou-Champasak Site

The Vat Phou - Champasak site lies on fertile alluvial plains on the banks of the Mekong River, and its mountainous core is the eastern outlier of the Dângrêk Range, which is home to the Phou Kao Mountains that rise up to an altitude of 1,416 meters.

The area of the Phou Kao Mountains is abundant in continental sandstones of fluvial origin, whereas the area on the eastern banks of the Mekong River is of extensive volcanic origin and consists mainly of basaltic lava and pyroclastic rocks overlaid with extensive lateritic deposits. Both sandstone and laterite were used for constructing the religious architectural structures, as revealed by the significant traces of quarrying activities. Most of the temples on and near the Phou Kao Mountains and on the alluvial plains were built mainly of sandstone, while laterite was used for limited purposes, such as the foundation of a building and walls. However, laterite was extensively utilized for the Tomo Temple Complex, which lies on the eastern banks of the Mekong River.

The Mekong River and its numerous tributaries are the main driving force behind the ongoing geological processes at the site. The flow level of the Mekong River is subject to seasonal variations depending on rainfall. During the monsoon season (July to October), the river level rises by up to 10~12 meters, overflowing its natural banks and often flooding the surrounding plains. Many tributaries (or Houay) flowing into the Mekong River illustrate the meandering waterways of the Champasak Plains, and all these tributaries often overflow and cause the flooding of low-lying areas during the monsoon season. The ancient city of Kurukshetra constructed brick/soil walls and moats to control the waterways. Ancient people reorganized waterways and implemented rainwater management through canals and barays for irrigation purposes and daily use. Thus, many hydraulic structures are found scattered across the site.