Sesan River is one of the largest tributaries of the Mekong River and has a drainage area of 17000 km2, where of 11000 km2 in Vietnam and 6100 km2 in Cambodia.
With its origin in the Central Highlands of Vietnam and the southernmost part of Laos the river flows through mountainous areas in Vietnams Dak Lak, Gia Lai and Kon Tum Provinces before entering North East Cambodia, where it moves into relatively lowland areas.
In Cambodia, Sesan winds from east to west through Ratanakiri Province and into Stung Treng Province, where it merges with the Srepok River, another large tributary of Mekong River. The resulting large river flows east where it flows into Se Kong River just before this river enters the Mekong River close to the Stung Treng Town
The rainy season lasts from August throughout November, with peaking flow normally in Sept-Oct. The precipitation varies from approximately 1000 mm in the lowlands in Cambodia to 2200 mm/y in the highlands of Vietnam.
There are two major cities on the Vietnamese side of the border, Kon Tum (13800 pe) and Plei Ku (170 000 pe). On the Vietnamese side, the river basin is situated in Kon Tum Province and in Gia Lai Province. The population density in these two provinces is 32 and 71 pe/km2, respectively (Statistical yearbook of Vietnam 1999).
After the building of Yale Hydropower Dam between 1996-2000, its regulation regime leads to flow change in the downstream, seriously affecting water use and ecosystem health for both Cambodia and Vietnam.
The meetings and conferences are holed with representatives from both Vietnam and Cambodia, which are working on how to solve the problems with the conflicting river use. Both countries are also member of the Mekong River Commission which is a co-operative forum for both utilization and protection of the Mekong River system, with tributaries.
Both Vietnam and Cambodia have to implement modern principles of water management to cope with the development of more intensive, and large scale water resources exploitation. In both countries this new water management organization has started, but there is still a long way to go to be able to secure the "rights" of all water use interests as well as the healthy aquatic environment. The Sesan case study is important as a transboundary case in Asia where there are a large number of such river basins.