Chapter 10 - Tonle Sap Lake, the Heart of the Lower Mekong

Abstract

Tonle Sap Great Lake, or Boeng Tonle Sap in Cambodian terminology, is the largest and most important natural freshwater lake in Southeast Asia. It plays a critical role in Cambodian Khmer culture, in the economy of Cambodia, and in the ecology and hydrology of the Mekong River basin. Boeng Tonle Sap comprises a permanent lake surrounded by an extensive floodplain. The permanent lake consists of two basins—a large northwest basin and a smaller southeast basin—linked by a relatively narrow strait. Tonle Sap Great Lake, like much of the rest of the Mekong River system of which it forms a component, is a monotonal flood-pulsed system. The dry season permanent lake begins to enlarge as floodwaters from the Mekong back up the Tonle Sap River. The sediment-laden water flows through channels in the low levees surrounding the dry season lake margins, and extends over the extensive surrounding floodplain, depositing its sediment as if flows. Tonle Sap Great Lake is of international significance culturally, hydrologically, and ecologically. Culturally it was the center of the great Khmer civilization from at least 800 AD to the 1440s. Hydrologically the lake provides a regulator for the flow of the Mekong River into the delta of Viet Nam. Ecologically it is a key component of one of the world's largest fisheries, and certainly the largest subsistence fishery.