Water

Water Action: Asia
Getting to Know the Mekong Wetlands
Tonle Sap, Cambodia

Tonle Sap Lake in western Cambodia is the largest lake in Southeast Asia. During the dry season it is drained by the Tonle Sap River southeast to the Mekong River. During the wet monsoon season from June to November, the rains and the melting of the snow pack in Tibet cause the Mekong to swell and the Tonle Sap River to reverse its flow, turning the Tonle Sap Basin into a great lake more than twice its original size. The flow reverses when the high waters of the Mekong River recede. The waters carry an abundance of fish, which are harvested and then dried to provide protein for Cambodia's inland rural population. At least 60% of the inland fisheries in production of Cambodia come from Tonle Sap Lake and Tonle Sap River.

The annual reversal of flow of the Tonle Sap River is so important to the economy and ecology of the region that the 1995 Agreement on Cooperation for the Sustainable Development of the Mekong River Basin specifically provides for its maintenance. This natural mechanism gives a unique and important balance to the Mekong River further downstream and ensures that freshwater flows into the Mekong Delta in Viet Nam during the dry season, as a buffer to saltwater intrusion into the rich agricultural lands of the delta.

The need to conserve Tonle Sap Lake was officially recognized in 1977, when the Government and the United Nations proposed the listing of the lake as a biosphere reserve. A Royal Decree on the Creation of the Tonle Sap Biosphere Reserve was made in February 2001. The reserve consists of three core areas surrounded by a buffer zone embedded in a transition zone. The core areas - Prek Toal, Boeng Chhmar, and Stung Sen - are designated for conservation, based on their importance for maintaining biodiversity.

Related Links

• The Tonle Sap Initiative: Future Solutions Now
• Living with Floods on Lake Tonle Sap
• Tonle Sap Photo Essay

Satellite Photo